mcq class 10 CBSE

MCQs  Class 10 Science

 Chapter 2: Acids, Bases and Salts

1. Some fruits like mango, lemon, raw grapes, orange, etc., have a sour taste due to the presence of:
a. Acetic acid
b. Citric acid
c. Lactic acid
d. Oxalic acid

Answer. b. Citric acid

2. Zinc granules on treating with an acid X, form the zinc sulphate (ZnSO4) salt along with the evolution of a gas Y which burns with a pop sound when brought near to a burning candle. Identify the acid X and gas evolved Y.
a. X- Sulphuric acid and Y- Oxygen gas
b. X- Hydrochloric acid and Y- Oxygen gas
c. X- Sulphuric acid and Y- Hydrogen gas
d. X- Hydrochloric acid and Y- Hydrogen gas

Answer. c. X- Sulphuric acid and Y- Hydrogen gas

3. The figure given below represents the experiment carried out between conc. sulphuric acid and sodium chloride, which react with each other to form HCl gas.

Blue litmus paper is brought near the mouth of the delivery tube to check the presence of HCl acid but no change is observed in the color of litmus paper because:

a. The litmus paper used is dry
b. The litmus paper used is moist
c. Blue litmus paper does not change its color with an acid
d. The litmus paper is kept very close to the mouth of the delivery tube

Answer. a. The litmus paper used is dry

4. Which of the following phenomena occur, when a small amount of acid is added to water?
i. Ionisation
ii. Neutralisation
iii. Dilution
iv. Salt formation

1. (i) and (ii)
2. (i) and (iii)
3. (ii) and (iii)
4. (ii) and (iv)

Answer. b. (i) and (iii)

5. Which of the following indicators turn red in an acidic solution?
i. Phenolphthalein 
ii. Litmus
iii. Turmeric
iv. Methyl orange

Choose the correct option:

1. (i) and (ii)
2. (ii) and (iii)
3. Only (ii)
4. (ii) and (iv)

Answer. d. (ii) and (iv)

6. Dilute acid does not produce carbon dioxide on being treated with:
a. Marble
b. Lime 
c. Baking soda
d. Limestone

Answer. b. Lime

7. The sample of soil from a particular place was tested for its pH value. It came out to be 5. Which one of the following should be added to the soil to make it suitable for the plant growth?
i. Calcium chloride
ii. Calcium Hydroxide
iii. Calcium oxide

Choose the correct option: 

1. Both (i) and (ii)
2. Both (ii) and (iii)
3. Only (i)
4. Only (iii)

Answer. b. Both (ii) and (iii)

8. Identify the products of the following reaction:

a. Calcium hydrogencarbonate and chlorine gas
b. Calcium chloride and water
c. Calcium oxide, carbon dioxide and water
d. Calcium chloride, carbon dioxide and water

Answer. d. Calcium chloride, carbon dioxide and water

9.  An ant’s sting can be treated with …………which will neutralise the effect of the chemical injected by the ant’s sting into our skin.
Choose the correct option from the following to be filled in the blank space:
a. Methanoic acid
b. formic acid
c. Baking soda
d. Caustic soda

Answer. c. Baking soda

10. In the following reaction, identify the salt formed 

NH₄OH (aq) + H₂SO₄ (aq) →  _____  +   2H₂O (l)

a. NH₄NO₃

b. (NH₄)₂SO₄

c. (NH₄)₃PO₄

d. (NH₄)₂S

Answer. b. (NH₄)₂SO₄

11. Which of the following salt will give acidic solution when dissolved in water?

a. NH₄Cl

b. NaCl

c. Na₂CO₃

d. CH₃COONa

Answer. a. NH₄Cl

12. Bleaching powder is used as a disinfectant for water to:
a. Make water tastier
b. Remove all the dirt from water
c. Make water germ-free
d. Make water clear

Answer. c. Make water germ-free

13. Which among the following represents the chemical formula for ‘Plaster of Paris’?

14. Which one of the following salts will dissolve in water to form an alkaline solution?
a. Potassium carbonate
b. Sodium chloride
c. Sodium carbonate
d. Potassium sulphate

Answer. a. Potassium carbonate

15. Copper sulphate crystals when heated strongly, lose their water of crystallization to give anhydrous copper sulphate accompanied by a change in color from:
a. Blue to green
b. Blue to white
c. Blue to sky blue
d. Blue to grey

Answer. b. Blue to white

Chapter 3: Metals and Non-Metals

1. The non-metal which is liquid at room temperature is:

a) Mercury

b) Bromine

c) Carbon

d) Helium

Answer: (b) Bromine

Explanation: Bomine is the only non-metal which exists as a liquid at room temperature.

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2. The number of protons in an atom of an element A is 19 then, the number of electron in its ion A⁺ is:

a) 18

b) 19

c) 20

d) 21

Answer: (a) 18

Explanation: In the neutral atom of an element,

3. Bauxite is an ore of

a) Iron

b) Aluminium

c) Mercury

d) Copper

Answer: (b) Aluminium

Explanation: Bauxite is a commercial ore of aluminium which consists largely of hydrated aluminium oxide, Al₂O₃.2H₂O. 

4. The metal which is liquid at room temperature is

a) Bromine

b) Mercury

c) Iodine

d) Potassium

Answer: (b) Mercury

Explanation: Mercury is the only metal which exists as a liquid at room temperature.

5. The sulphide ores are converted into oxides by heating strongly in the presence of excess air. This process is known as

a) Roasting

b) Smelting

c) Calcination

d) Refining

Answer: (a) Roasting

Explanation: The process of heating the sulphide ore strongly in the presence of air to convert it into metal oxide, is known as roasting.

6. In electrolytic refining, the cathode is made up of

a) Pure metal

b) Impure metal

c) Alloy

d) Metallic salt

Answer: (a) Pure metal

Explanation: In electrolytic refining of a metal, the cathode is made up of pure metal whereas the anode is made up of impure metal.

7. In the given reaction, Al₂O₃ + NaOH   →  ……X……   +  H₂O

What is element X?

a) NaAlO₂

b) Na₃Al

c) Na₂O₃

d) NaAl₂O₃

Answer: (a) NaAlO₂

Explanation: Aluminium oxide is amphoteric in nature, i.e., it reacts with acids as well as bases to form salt and water.

Here, aluminium oxide behaves as an acid as it reacts with NaOH, a base and forms sodium aluminate (NaAlO₂) and water:

                                   Al₂O₃ + NaOH   →  2NaAlO₂+  H₂O

8. Which of the following represent the correct order of decreasing reactivity?

a) Mg > Al > Zn > Fe

b) Mg > Zn > Al > Fe

c) Al > Zn > Fe > Mg

d) Mg > Fe > Zn > Al

Answer: (a) Mg > Al > Zn > Fe

Explanation: The decreasing order of the reactivity of the common metals is given below:

            Li, K, Na, Ba, Ca, Mg , Al, Mn, Zn, Fe, Ni, Sn, Pb, [H], Cu,Hg, Ag, Au,Pt 

9. An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be

(a) Ca

(b) C

(c) Si

(d) Fe

Answer: (a) Ca

Explanation:                         

Calcium reacts with oxygen to give calcium oxide (CaO) which is having a high melting point and dissolves in water to  form calcium hydroxide (Ca(OH)₂)along with the release of large amount of thermal energy.

10. Which of the following pairs will give displacement reactions?

(a) NaCl solution and copper metal

(b) MgCl₂ solution and aluminium metal

(c) FeSO₄ solution and silver metal

(d) AgNO₃ solution and copper metal

Answer: (d) AgNO₃ solution and copper metal

Explanation: Copper (Cu) being more reactive than silver (Ag), displaces silver from silver nitrate (AgNO₃) to form copper nitrate

                                                                 2AgNO₃ + Cu  →  Cu(NO₃)₂+  2Ag

11. Which among the following is the most abundant metal found in the earth’s crust?

(a) Magnesium

(b) Aluminium

(c) Oxygen

(d) Iron

Answer: (b) Aluminium

Explanation: Aluminium is the most abundant metal found in the earth’s crust.

12. Which of the following pairs of reactants will go undergo a displacement reaction?

(a) CuSO₄ + Fe 

(b) ZnSO₄ + Fe

(c) MgSO₄ + Fe

(d) Ca(SO₄)₂ + Fe

Answer: (a) CuSO₄ + Fe

Explanation: As per the reactivity series of metals, iron is more reactive than copper metal so it can displace copper from copper sulphate solution and form iron (II) sulphate and copper:                     

13. Galvanisation is a method of protecting steel and iron from rusting by coating them with a thin layer of

(a) Copper

(b) Aluminum

(c) Zinc

(d) Bauxite

Answer: (c) Zinc

Explanation: In this method a thin layer of zinc metal is deposited over the surface of steel or iron objects, which does not corrode on exposure to damp air and prevents the coated metals from rusting.

14. Which of the following alloys contains a non-metal as one of its constituents?

(a) Steel

(b) Brass

(c) Amalgam

(d) Bronze

Answer: (a) Steel

Explanation: Stainless steel is an alloy of iron (a metal) and carbon (a non metal).

15. An element X is soft and can be cut with the help of a knife. It is very reactive to air and cannot be kept open in the air. It reacts vigorously with water. Identify the element from the following:

(a) Mg

(b) Na

(c) P

(d) Ca

Answer: (b) Na

Explanation: Na is a metal which is soft enough to be cut with a knife. It is so reactive that it reacts vigorously with air or moisture and catches fire when kept in open. So to prevent it from coming in contact with oxygen and moisture, it is kept in kerosene.

 Chapter 4: Carbon and its Compounds

1. Which of the following structures correctly represents the electron dot structure of a chlorine molecule?

Answer: (a)

Explanation: In an electron dot structure of a molecule there must be shown eight electrons (in the form of dots or crosses) around each element of the molecule, to represent the complete octet of the element.

2. While cooking, if the bottom of the vessel is getting blackened on the outside, it means that:

a) The food is not cooked completely

b) The fuel is not burning completely

c) The fuel is wet

d) The fuel is burning completely

Answer: (b) The fuel is not burning completely

Explanation: In case the fuel doesn’t burn completely, i.e., there is not enough oxygen to react with the carbon to produce carbon dioxide, then the unburnt carbon particles are left behind in the form of black particles known as soot. These soot particles stick to the bottom of the vessel making it black.

3. Cation is formed when:

a) Atom gains electrons

b) Atom loses electrons

c) Proton is lost by the atom

d) Atom shares electrons

Answer: (b) Atom loses electrons

Explanation: A cation is formed by loss electrons from the atom of an element which acquires positive charge due to the presence of greater number of protons as compared to that of electrons.

4. The I.U.P.A.C name of CH₃CH₂CH=CH₂ is?

a) 3-Butene

b) Prop-1-ene

c) But-1-ene

d) Butyne

Answer: (c) But-1-ene

Explanation: As the compound, CH₃CH₂CH=CH₂ contains four carbon atoms and a double bond attached to the first carbon, so the I.U.P.A.C name of CH₃CH₂CH=CH₂ is But-1-ene.

5. Which of the following compounds of carbon does not consist of ions?

a) CHCl₃

b) CaCO₃

c) NaHCO₃

d) Ca₂C

Answer: (a) CHCl₃

Explanation: Carbon always forms covalent compounds by sharing its electrons with other atoms. Now, in covalent bonding, the two electrons shared by the atoms are attracted to the nucleus of both atoms and neither atom completely loses or gains electrons as in ionic bonding. So the compounds in which all the atoms are directly attached to C-atom, contain covalent bonding and no ionic bond.

In CHCl₃, all the three chlorine atoms are bonded covalently to the carbon atom, not to the hydrogen atom. So CHCl₃ is a covalent compound and does not consist of ions.

6. The property of self-linkage among identical atoms to form long chain compounds is known as:

a) Catenation

b) Isomerisation

c) Superposition

d) Halogenation

Answer: (a) Catenation

Explanation: Catenation is the property of self-linking of an element by which an atom combines with the other atoms of the same element to form long chains.

7. Which of the following is the molecular formula of cyclobutane?

a) C₄H₁₀

b) C₄H₆

c) C₄H₈

d) C₄H₄

Answer: (c) C₄H₈

Explanation: Cyclobutane is a cyclic hydrocarbon consisting of four carbon atoms where each carbon atom is attached to the two other carbon atoms and two hydrogen atoms, as shown below:

                                                           

8. Which of the following statements about graphite and diamond is true?

a) They have the same crystal structure

b) They have the same degree of hardness

c) They have the same electrical conductivity

d) They can undergo the same chemical reactions

Answer: (d) They can undergo the same chemical reactions

Explanation: Both Graphite and diamond being the allotropes of the same element , carbon, have similar chemical properties. So they undergo the same chemical reactions.

9. How many number of carbon atoms are joined in a spherical molecule of buckminsterfullerene?

a) 30

b) 60

c) 90

d) 120

Answer: (b) 60

Explanation: Buckminsterfullerene is a molecule of carbon in the form of a hollow sphere consisting of 60 C-atoms and is having the formula C₆₀.

10. Which of the followings is the major constituent of the liquefied petroleum gas?

a) Methane

b) Ethane

c) Propane

d) Butane

Answer: (d) Butane

Explanation: The major constituent of the liquefied petroleum gas is butane.

11. The organic compounds having functional group are known as:

a) Aldehyde

b) Ketone

c) Carboxylic acids

d) Alcohol

Answer: (c) Carboxylic acids

Explanation: Carboxylic acids are compounds which contain a group also known as carboxyl group. 

12. From which of the following substance pencil lead is formed?

a) Charcoal

b) Wood

c) Lead

d) Graphite

Answer: (d) Graphite

Explanation: Pencil lead is formed of graphite. Graphite is an allotropic form of carbon in which each carbon atom is joined to three others, forming layers:

These layers are put together by weak van der Waals forces which enable the layers to slide over each other, making graphite soft and slippery. So graphite is used as pencil ‘lead’. As the pencil moves across the paper, layers of graphite rub off leaving the dark marks on paper.

13. Ester is formed by the reaction between:

a) An acid and an alcohol

b) An acid and a base

c) A base and an alcohol

d) An acid and an alkene

Answer: (a) An acid and an alcohol

Explanation: Reaction between an acid and an alcohol results in the formation of ester, and the reaction is named as estrification.

For example: Acetic acid reacts with ethyl alcohol in the presence of concentrated sulphuric acid to form Ethyl acetate:

         

14. What is denatured alcohol?

a) Ethyl alcohol which has been made unfit for drinking purpose by adding small amount of poisonous substance

b) Methyl alcohol which has been made unfit for drinking purpose by adding small amount of poisonous substance

c) Alcohol having properties of an acid

d) Ethyl alcohol containing 60% of water by weight

Answer: (a) Ethyl alcohol which has been made unfit for drinking purpose by adding small amount of poisonous substance

Explanation: Denatured alcohol is the ethyl alcohol which has been made unfit for drinking purpose by adding small amount of poisonous substance like methanol, pyridine, etc. This is mainly done to prevent the misuse of industrial alcohol for drinking purposes.

15. Which of the following substance produces brisk effervescence with baking soda solution?

a) Ethanoic acid

b) Table salt

c) Vinegar

d) Sunflower oil

Answer: (a) Ethanoic acid

Explanation: Ethanoic acid when treated with baking soda (Sodium hydrogencarbonate) gives brisk effervescence of Carbon dioxide gas.

           

 Chapter 6: Life Processes

1. Which of the following is not a digestive enzyme contained in the pancreatic juice?

i. Lipase

ii. Hydrochloric acid

iii. Mucus

iv. Trypsin

          a) (i) and (ii)

          b) (i) and (iv)

          c) (ii) and (iii)

          d) (i) and (iii)

Answer: (c) (ii) and (iii)

Explanation: The enzymes lipase and trypsin are present in the pancreatic juice that breakdown emulsified fats and degrade proteins respectively.

2. The enzymes pepsin and trypsin are secreted respectively by

a) Stomach and pancreas

b) Salivary gland and stomach

c) Liver and pancreas

d) Liver and salivary gland

Answer: (a) Stomach and pancreas

Explanation: Stomach secretes the enzyme pepsin and pancreas produces trypsin. Both of them breakdown protein.

3. Among the following choose the correct option which includes the organisms that have a holozoic mode of nutrition:

a) Plasmodium and Amoeba

b) Parakeet and Amoeba

c) Paramecium and Plasmodium

d) Paramecium and Parasite

Answer: (b) Parakeet and Amoeba

Explanation: Holozoic nutrition involves the ingestion of organic food particles and later its assimilation for the purpose of supplying energy to the whole body.

4. Raw materials required in the autotrophic mode of nutrition involves:

i. Carbon dioxide and water

ii. Chlorophyll

iii. Nitrogen

iv. Sunlight

          a) (i), (ii) and (iii)

          b) (i) and (ii)

          c) (i), (ii) and (iv)

          d) All (i), (ii), (iii) and (iv)

Answer: (c) (i), (ii) and (iv)

Explanation: Autotrophic mode of nutrition involves the use of sunlight, chlorophyll, carbon dioxide and water to produce starch.

5. The enzymes contained in pancreatic juices help in the digestion of:

a) Fats and carbohydrates

b) Proteins and fats

c) Proteins and carbohydrates

d) Proteins, fats and carbohydrates

Answer: (d) Proteins, fats and carbohydrates

Explanation: The pancreas contains all kinds of enzymes that can digest proteins, fats and carbohydrates.

6. Which of the following help in protecting the inner lining of the stomach from the harmful effect of hydrochloric acid?

a) Mucus

b) Pepsin

c) Trypsin

d) Bile

Answer: (a) Mucus

Explanation: Mucus is a viscous secretion that protects the inner lining of the stomach from the action of HCl.

7. Sometimes we get painful cramps in our leg muscles after running for a long time due to the accumulation of:

a) Hydrochloric acid

b) Fat

c) Carbon dioxide

d) Lactic acid

Answer: (d) Lactic acid

Explanation: The build-up of lactic acid in our muscles while running (less oxygen conditions) causes cramps.

8. The vein which brings clean blood from the lungs into the heart is known as:

a) Pulmonary vein

b) Hepatic vein

c) Superior vena cava

d) Pulmonary artery

Answer: (a) Pulmonary vein

Explanation: The pulmonary vein is responsible for bringing oxygenated and pure blood into the heart.

9. Movement of the synthesized products from the leaves to the roots and other parts of a plant’s body takes place through the phloem. This process is known as:

a) Translocation

b) Transpiration

c) Transportation

d) Excretion

Answer: (a) Translocation

Explanation: The transport of soluble products of photosynthesis through all parts of the plant by specialized structures called phloem is translocation.

10. The process of diffusion of solvent particles from the region of less solute concentration to a region of high solute concentration through semi-permeable membrane is known as

a) Diffusion

b) Osmosis

c) Translocation

d) Transpiration

Answer: (b) Osmosis

Explanation: The diffusion of solvent particles from a region of less concentration to high concentration (concentration gradient) through a semi permeable membrane is called osmosis.

11. Which among the following procedures is used for cleaning the blood of a person by separating the waste substance from it?

a) Kidney transplant

b) Blood transfusion

c) Dialysis

d) Hydrolysis

Answer: (c) Dialysis

Explanation: Dialysis is the procedure of detoxifying the blood by isolating the waste and unwanted constituents in it.

12. The excretory unit of the human excretory system is known as:

a) Nephridia

b) Neuron

c) Nephron

d) kidneys

Answer: (c) Nephron

Explanation: Each kidney has large numbers of the filtration units called nephrons.

13. Plants use the energy stored in ATP to accomplish the process of transportation of:

a) Water and minerals

b) Oxygen

c) Water, minerals and food

d) Food

Answer: (d) Food

Explanation: Translocation of food by phloem is achieved by utilizing energy from ATP.

14. Which among the following is necessary to carry out the blood coagulation in a cut or wound?

a) White Blood Cells

b) Blood plasma

c) Platelets

d) Red blood cells

Answer: (c) Platelets

Explanation: Platelets coagulate blood whenever there is a cut or a wound. This stops excess flow of blood or hemorrhagic conditions.

15. Arteries and veins are connected by a network of extremely narrow tubes called:

a) Sieve tubes

b) Capillaries

c) Vena cava

d) Valves

Answer: (b) Capillaries

Explanation: Blood capillaries are vessels that connect arteries and veins and help in blood circulation.

 Chapter 8: How Do Organisms Reproduce

1. Which among the following is a unicellular organism that reproduces by budding:

(a) Hydra

(b) Planaria

(c) Yeast

(d) Spirogyra

Answer. (c) Spirogyra

2. Which among the following does not reproduce by spore formation:

(a) Penicillium fungus

(b) Yeast fungus

(c) Mucor fungus

(d) Rhizopus fungus

Answer. (b) Yeast fungus

3. The rapid spreading of bread mould on slices of bread are due to:

(i) Presence of large number of spores in air

(ii) Presence of large number of thread-like branched hyphae

(iii) Presence of moisture and nutrients

(iv) Formation of round shaped sporangia

(a) (i) and (iii)

(b) (ii) and (iv)

(c) (i) and (ii)

(d) (iii) and (iv)

Answer. (a) (i) and (iii)

4. The asexual reproduction in the Spirogyra involves:

(a) Breaking up of filaments into smaller bits

(b) Division of a cell into many cells

(c) Division of a cell into two cells

(d) Formation of a large number of buds

Answer. (b) Division of a cell into many cells

5. Reason for the greater similarities among the offsprings produced by asexual reproduction, is:

(i) Asexual reproduction involves only one parent

(ii) Asexual reproduction involves two parents

(iii) Asexual reproduction involves gametes

(iv) Asexual reproduction does not involve gametes

(a) (i) and (ii)

(b) (i) and (iii)

(c) (ii) and (iv)

(d) (i) and (iv)

Answer. (d) (i) and (iv)

6. The process of the division of cell into several cells during reproduction in Plasmodium is termed as:

(a) Fragmentation

(b) Budding

(c) Multiple fission

(d) Binary fission

Answer. (c) Multiple fission

7. The number of chromosomes in parents and offsprings of a particular species remains constant due to:

(a) Doubling of chromosomes after zygote formation

(b) Halving of chromosomes during gamete formation

(c) Doubling of chromosomes after gamete formation

(d) Halving of chromosomes after gamete formation

Answer. (b) Halving of chromosomes during gamete formation

8. A Planaria worm is cut horizontally in the middle into two halves P and Q such that the part P contains the whole head of the worm. Another Planaria worm is cut vertically into two halves R and S in such a way that both the cut pieces R and S contain half head each. Which of the cut pieces of the two Planaria worms could regenerate to form the complete respective worms?

(a) Only P

(b) Only R and S

(c) P, Rand S

(d) P, Q, R and S

Answer. (d) P, Q, R and S

9. The number of chromosomes in both parents and offsprings of a particular species remains constant because:
(a) Chromosomes get doubled after zygote formation

(b) Chromosomes get doubled after gamete formation

(c) Chromosomes get halved during gamete formation

(d) Chromosomes get halved after gamete formation

Answer. (c) Chromosomes get halved during gamete formation

10. The figure given alongside shows the human male reproductive organs. Which structures make sperms and seminal fluid?

(a) V makes sperms and X makes seminal fluid

(b) W makes sperms and Y makes seminal fluid

(c) X makes sperms and W makes seminal fluid

(d) Y makes sperms and V makes seminal fluid

Answer. (d) Y makes sperms and V makes seminal fluid

11. An organism capable of reproducing by two asexual reproduction methods one similar to the reproduction in yeast and the other similar to the reproduction in Planaria is:

(a) Spirogyra

(b) Hydra

(c) Bryophyllum

(d) Paramecium

Answer. (b) Hydra

12. Among the following select the statements that are true regarding the sexual reproduction in flowering plants?

(i) Fertilisation is a compulsory event

(ii) It always results in the formation of zygote

(iii) Offsprings formed are clones

(iv) It requires two types of gametes

(a) (i) nad (iv)

(b) (i), (ii) and (iii)

(c) (i), (ii) and (iv)

(d) (ii), (iii) and (iv)

Answer. (c) (i), (ii) and (iv)

13. Which among the following are not the functions of testes at puberty?

(i) Formation of germ cells

(ii) Secretion of testosterone

(iii) Development of placenta

(iv) Secretion of estrogen

(a) (i) and (ii)

(b) (i) and (iii)

(c) (ii) and (iv)

(d) (iii) and (iv)

Answer. (d) (iii) and (iv)

14. Which out of the following processes does not lead to the formation of clones:

(a) Fertilisation

(b) Fission

(c) Tissue culture

(d) Fragmentation

Answer. (a) Fertilisation

15. The ratio of number of chromosomes in a human zygote and a human sperm is:

(a) 2 : 1

(b) 3 : 1

(c) 1 : 2

(d) 1 : 3

Answer. (a) 2 : 1