Chemistry Jamb Practice CBT Questions & Answers 2021

 

 Chemistry Jamb Practice CBT Questions & Answers 2021

SET 1

1.A given amount of gas occupies 10.0dm5 at 4atm and 273°C. The number of moles of the gas present is [Molar volume of gas at s.t.p = 22.4dm]
A. 0.89 mol
B. 1.90 mol
C. 3.80 mol
D. 5.70 mol

Correct Answer: Option A


2.According to Charles' law, the volume of a gas becomes zero at

A. 0°C
B. -100°C
C. -273°C
D. -373°C

Correct Answer: Option C



3.A substance that is used as a ripening agent for fruits is

A. ethene
B. propane
C. methane
D. butane

Correct Answer: Option A



4. The Sulphide which is insoluble in dilute hydrochloric acid is

A. FeS
B. CuS
C. ZnS
D. Na2S

Correct Answer: Option B


5.What is the PH of 0.00 1 moldm


solution of the sodium hydroxide
A. 14
B. 13
C. 12
D. 11

Correct Answer: Option D



6. The type of bonding in [Cu(NH)]


is
A. coordinate
B. electrovalent
C. metallic
D. covalent

Correct Answer: Option A


7.Which of the following is an example of a chemical change?

A. dissolution of salt in water
B. rusting of iron
C. melting of ice
D. separating a mixture by distillation

Correct Answer: Option B



8.To what temperature must a gas at 273k be heated in order to double both its volume and pressure?

A. 298K
B. 546K
C. 819K
D. 1092K

Correct Answer: Option D


9.According to the Kinetic Theory an increase in temperature causes the kinetic energy of particles to

A. decrease
B. increase
C. be zero
D. remain constant


Correct Answer: Option B
Explanation

According to the kinetic theory of gases, when a substance is heated, the average kinetic energy of its molecules increases and this leads to a rise in temperature.



10.An element used in the production of matches is


A. nitrogen
B. aluminium
C. copper
D. sulphur

Correct Answer: Option D



11.Which of the following gases may not be dried with concentrated sulphuric acid?

A. HCl

B. NH
C. Cl
D. SO


12.The Consecutive members of an alkane homologous series differ by

A. CH
B. CH

C. CHD. CH

Correct Answer: Option B

13.A correct electrochemical series can be obtained from Na, Ca, Al, Mg, Zn, Fe, Pb, H, Cu, Hg, Ag, Au by interchanging

A. Al and Mg
B. Zn and Fe
C. Zn and Pb
D. Pb and H

Correct Answer: Option A

14.A basic postulate of the kinetic theory of gases is that the molecules of a gas move in straight lines between collisions. This implies that

A. collisions are perfectly elastic
B. forces of repulsion exist
C. forces of repulsion and attraction are in equilibrium
D. collisions are inelastic

Correct Answer: Option B


15.On which of the following is the solubility of a gaseous substance dependent?


I. Nature of solvent

II. Nature of solute

III. Temperature

IV. Pressure
A. I, II, III and IV
B. I and II only
C. II only
D. I, III and IV only

Correct Answer: Option D


16. Which of the following statements is correct about the periodic table?

A. Elements in the same period have the same number of valence electrons
B. The valence electrons of the elements in the same period increase progressively across the period
C. Elements in the same group have the same number of electron shells
D. The non-metallic Properties of the elements tend to decrease across each period

Correct Answer: Option B
Explanation

The valence electrons refer to the number of electrons in the outer shell. Across a period (horizontal row), the valence electron increases.



17. The periodic classification is an arrangement of the elements

A. atomic weights
B. isotopic weights
C. molecular weights
D. atomic numbers


Correct Answer: Option D
Explanation

Elements in the periodic table are arranged according to their atomic number (proton number). Electronegativity increase from left to right while atomic radius increases down the group

Elements in the periodic table are arranged according to their atomic number (proton number). Electronegativity increase from left to right while atomic radius increases down the group


18. If 1 litre of 2.2M sulphuric acid is poured into a bucket containing 10 litres of water and the resulting solution mixed thoroughly, the resulting sulphuric acid concentration will be

A. 2.2M
B. 1.1M
C. 0.22M
D. 0.11M


Correct Answer: Option C



19





In the shown experiment (Fig. 1) the litmus paper will initially
A. be bleached
B. turn green
C. turn red
D. turn blue


Correct Answer: Option D


20. The boiling of fat and aqueous caustic soda is referred to as
A. hydrolysis
B. esterification
C. acidification
D. saponification



Correct Answer: Option D



21. Which of the following pairs of substances will react further with oxygen to form a higher oxide?

A. CO and HO

B. NO and HO

C. CO and CO

D. SO and NO



Correct Answer: Option D



22. In the preparation of oxygen by heating KCIO, in the presence of MnO

only moderate heat is needed because the catalyst acts by
A. lowering the pressure of the reaction
B. increasing the surface area of the reaction
C. increasing the rate of the reaction
D. lowering the energy barrier of the reaction

Correct Answer: Option D


23.Methanoic acid mixes with water in all proportions and has about the same boiling point as water. Which of the following methods would you adopt to obtain pure water from a mixture of Sand, water and methanoic acid?

A. Fractional distillation
B. Filtration followed by distillation
C. Neutralization with sodium hydroxide followed by distillation
D. Neutralization with sodium hydroxide followed by filtration

Correct Answer: Option B
Explanation

the first process would be FILTRATION in order to remove the sand, then DISTILLATION is used to separate the liduid.


24. A quantity of electricity liberates 3.6g of Silver from its salt. What mass of aluminium Will be liberated from its salt by the same quantity of electricity? [Al = 27, Ag = 108].

A. 2.7g
B. 1.2g
C. 0.9g
D. 0.3g

Correct Answer: Option A


25.Suitable reagents for the laboratory preparation nitrogen are
A. sodium dioxonitrate(III) and ammonium chloride
B. sodium trioxonitrate(V) and ammonium chloride
C. sodium chloride and ammonium trioxonitrate(V)
D. sodium chloride and ammonium di-ozonitrate(III)
Correct Answer: Option A

26. The number of electrons in the valence shell of an element of atomic number 14 is?

A. 1
B. 2
C. 3
D. 4
Correct Answer: Option D