Some Basic Concepts of Chemistry Multiple Choice Questions and Answers

1 If water sample are taken from sea, rivers or lake, they will be found to contain hydrogen and oxygen in the approximate ratio of 1 : 8.This indicates the law of :

A Multiple proportion

B Definite proportion

C Reciprocal proportions

D None of these

View Answer

Answer: Definite proportion

2 Mass of one atom of the element A is 3.985410-23. How many atoms are contained in 1 gm of the element A?

A 2.509 1023

B 6.022 1023

C 12.044 1023

D None of these

View Answer

Answer: None of these

3 Which of the following contains the largest mass of hydrogen atoms?

A 5.0 moles C2H2O4

B 1.1 moles C3H8O3

C 1.5 moles C6H8O6

D 4.0 moles C2H4O2

View Answer

Answer: 4.0 moles C2H4O2

4 Rearrange the following (I to IV) in the order of increasing masses :

(I) 0.5 mole of O3

(II) 0.5 gm atom of oxygen

(III) 3.011 1023molecules of O2

(IV) 5.6 litre of CO2 at STP

A II< IV < II < I

B II < I < IV < III

C IV < II < III < I

D None of the above

View Answer

Answer: II < IV < III < I

5 The total no. of neutrons present in 54 mL H2O (l) are :

A 3 NA

B 30 NA

C 24 NA

D None of these

View Answer

Answer: 24 NA

6 The number of neutron in 5 g of D2O (D is H) are :

A 0.25 NA

B 2.5 NA

C 1.1 NA

D None Of The Above

View Answer

Answer: 2.5 NA

7 Calculate number of atoms is 60 g of C–12

A 3.01  1022

B 30.1  1023

C 5

D 5  1023

View Answer

Answer: 30.1  1023

8 How many years it would take to spend Avogadro’s number of rupees at the rate of 10 lac rupees per second

A 1.9099  1010 years

B 3.9099  1010 years

C 1.9099  1012 years

D None of these

View Answer

Answer: 1.9099  1010 years

9 The dot at the end of this sentence has a mass of about one microgram. Assuming that the black stuff is carbon, number of atoms of carbon needed to make such a dot is approximately

A 5  1012 atoms

B 5  1014 atoms

C 5  1016 atoms

D 5  1018 atoms

View Answer

Answer: 5  1016 atoms

10 Density of a 2.05 M solution of acetic acid in water is 1.02 g/mL. The molality of the solution is:

A 1.14 mol kg–1

B 3.28 mol kg–1

C 2.28 mol kg–1

D 0.44 mol kg–1

View Answer

Answer: 2.28 mol kg–1

11 When 50 mL of 2.00 M HCl, 100 mL of 1.00 M HCl and 100mL of 0.500 M HCl are mixed together, the resulting HCl concentration of the solution is

A 0.25 M

B 1.00 M

C 3.50 M

D 6.25 M

View Answer

Answer: 1.00 M

12 3.0 molal NaOH solution has a density of 1.110 g/mL. The molarity of the solution is:

A 2.95

B 3.05

C 3.64

D None of the above

View Answer

Answer: 2.95

13 In the aqueous solution of sulphuric acid, the mole fraction water is 0.85. The molality of the solution is:

A 8.9 m

B 0.19 m

C 9.8 m

D 15 m

View Answer

Answer: 9.8 m

14 The number of HCl molecules present in 1 cm3 of its 1M solution is

A NA

B 0.1 M

C 10–3 NA

D none of these

View Answer

Answer: 10–3 NA

15 Calculate the mass of anhydrous HCl in 10 mL of concentrated HCl (density = 1.2 g/mL) solution having 37% HCl by weight.

A 4.44 g

B 4.44 mg

C 4.44  10–3 g

D None of these

View Answer

Answer: 4.44 g

16 The major commercial source of bromine is USA is deep brine wells in Arkansas where the concentration of bromide ion can be as high as 5000 parts for million by mass. What is the concentration when expressed as a mass percentage?

A 0.005%

B 0.05%

C 0.5%

D 5%

View Answer

Answer: 0.5%

17 The mole fraction of solute in one molal aqueous solution is:

A 0.009

B 0.018

C 0.027

D 0.036

View Answer

Answer: 0.018

18 A solution has 25% of water, 25% ethanol and 50% acetic acid by mass. The mole fraction of water is

A 0.5

B 0.25

C 0.75

D 0.6

View Answer

Answer: 0.5

19 A 20.0 mL sample of 0.200 molar K2CO3 solution is added to 30.0 mL of 0.400 molar Ba(NO3)2 solution. Barium carbonate precipitates. The concentration of Barium ion, Ba+2, in the solution, after reaction is

A 0.4

B 0 M

C 0.267 M

D 0.16 M

View Answer