Some Basic Concepts of Chemistry Objective Type Questions and Answers

Questions

21 What volume 0.8 M solution contains 0.1 mole of solute?

A 100 mL

B 125 mL

C 500 mL

D None of these

Answer: 125 mL

22 Naturally occurring thallium consists of two stable isotopes, Tl-203 and Tl-205 (atomic mass = 203.0 and 205.0, respectively) and has an average atomic mass of 204.4. What is percentage of Tl – 205?

A 14.0%

B 30.0%

C 70.0%

D None of these

View Answer

Answer: 70.0%

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23 Total mass of 1 mole of CO2 + 10 g mole of O2 + 5 g molecule of SO3 + 5 g atom of Na + 10 g of SO3 + 5 g of Na atom

A 764 g

B 879 g

C 894 g

D None of these

View Answer

Answer: 894 g

24 Four containers of 2 L capacity contains dinitrogen as described below. Which one contains maximum number of molecules?

A 2.5 g molecule of N2

B 4 g atom of nitrogen

C 82 g of dinitrogen

D None of the above

View Answer

Answer: 82 g of dinitrogen

25 Which of the following represents 1 g mole of the substance

A 6.02  1023 molecules of NH3

B 4 g of He

C 56 g of CaO

D None of these

View Answer

Answer: 4 g of He

26 The maximum volume of STP is occupied by

A 1 g molecule of CO2

B 1 g of CO2 of molecule

C 44.5 g of CO2

D None Of The Above

View Answer

Answer: 44.5 g of CO2

27 one gram atom of Nitrogen atom corresponds to

A NA molecules of N2

B 11.2 L of N2 at STP

C 14 g of N2

D 22.4 L of N2 at STP

View Answer

Answer: 11.2 L of N2 at STP

28 The number of moles of oxygen in 1 L of air containing 21% oxygen by volume, in standard conditions, is

A 0.186 mol

B 0.21 mol

C 0.0093 mol

D None of these

View Answer

Answer: 0.0093 mol

29 4 g of an unknown gas occupies 2.24 L of volume at Standard temperature and pressure. The gas may be

A Carbon dioxide

B Carbon monoxide

C Oxygen

D Sulphur dioxide

View Answer

Answer: Carbon dioxide

30 In a mole of water vapours at STP, the volume actually occupied or taken by the molecules (i.e., Avogadro’s No. x volume of one molecule) is

A Zero

B Less than 1% of 22.4 L

C About 10% of the volume of container

D 1% to 2% of 22.4 L

View Answer

Answer: 1% to 2% of 22.4 L

31 The mass of 112 cm3 of CH4 gas at STP is

A 0.16 g

B 0.8 g

C 0.08 g

D 1.6 g

View Answer

Answer: 0.08 g

32 32 g O2, 2 g H2 and 28 g N2 at STP occupy separately a volume of

A 1 L

B 2 L

C 22.4 L

D None of the above

View Answer

Answer: 22.4 L

33 Which of the following contains maximum number of molecules?

A 100 cc of CO2 at STP

B 150 cc of N2 at STP

C 50 cc of SO2 at STP

D 150 cc of O2 at STP

View Answer

Answer: 50 cc of SO2 at STP

34 The maximum number of molecules is present in

A 10 g of O2 gas

B 15 L of H2 gas at STP

C 5 L of N2 gas at STP

D none of these

View Answer

Answer: 15 L of H2 gas at STP

35 An alkaloid contains 17.28% of nitrogen and its molecular mass is 162. The number of nitrogen atoms present in one molecule of alkaloid is:

A Five

B Four

C Three

D Two

View Answer

Answer: Two

36 How many atoms are contained in one mole of sucrose (C12H22OH)?

A 45  6.02  1023 atoms/mole

B 5  6.62  1023 atoms/mole

C 5  6.02  1023 atoms/mole

D None of these

View Answer

Answer: 45  6.02  1023 atoms/mole

37 The largest number of molecules is in

A 34 g of water

B 28 g of CO2

C 46 g of CH3COH

D 54 g of N2O5

View Answer

Answer: 34 g of water

38 One mole of CO2 contains

A 6.02  1023 atoms of C

B 6.02  1023 atoms of O

C 18.1  1023 molecules of CO2

D 3 gram of carbon

View Answer

Answer: 6.02  1023 atoms of C

39 How many molecules are present in one gram of hydrogen?

A 6.02  1023

B 3.01  1023

C 2.5  1023

D 1.5  1023

View Answer

Answer: 3.01  1023

40 0.2 mole of HCl and 0.2 mole of barium chloride were dissolved in water to produce a 500 mL solution. The molarity of the Cl– ions is:

A 0.06 M

B 0.09 M

C 1.2 M

D None Of The Above

View Answer

Answer: 1.2 M

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