Some Basic Concepts of Chemistry

An element, X has the following isotopic composition: 200X : 90\% 199X : 8.0\% 202X : 2.0\% The weighted average atomic mass of the naturally occurring element X is closest to

1. 201 amu
2. 202 amu
3. 199 amu
4. 200 amu

Concentrated aqueous sulphuric acid is 98% H2SO4 by mass and has a density of 1.80 g mL-1. Volume of acid required to make one litre of 0.1 M H2SO4 solution is

1. 16.65 mL
2. 22.20 mL
3. 5.55 mL
4. 11.10 mL

The maximum number of molecules is present in

1. 15 L of H2 gas at STP
2. 5 L of N2 gas at STP
3. 0.5 g of H2 gas
4. 10 g of O2 gas

In Haber process 30 litres of dihydrogen and 30 litres of dinitrogen were taken for reaction which yielded only 50% of the expected product. What will be the composition of gaseous mixture under the aforesaid condition in the end ?

1. 20 litres ammonia, 20 litres nitrogen, 20 litres hydrogen
2. 10 litres ammonia, 25 litres nitrogen, 15 litres hydrogen
3. 20 litres ammonia, 10 litres nitrogen, 30 litres hydrogen
4. 20 litres ammonia, 25 litres nitrogen, 15 litres hydrogen

Which has maximum molecules?

1. 7 g N2
2. 2 g H2
3. 16 g NO2
4. 16 g O2

The percentage of C, H and N in an organic compound are 40%, 13.3% and 46.7% respectively then empirical formula is

1. C3H13N3
2. CH2N
3. CH4N
4. CH6N

2.5 litre of 1 M NaOH solution is mixed with another 3 litre of 0.5 M NaOH solution. Then find out molarity of resultant solution.

1. 0.80 M
2. 1.0 M
3. 0.73 M
4. 0.50 M

Percentage of Se in peroxidase anhydrous enzyme is 0.5\% by weight (at. wt. = 78.4), then the minimum molecular weight of peroxidase anhydrous enzyme is

1. 1.568 104
2. 1.568 103
3. 15.68
4. 2.136 104

Molarity of liquid HCl, if density of solution is 1.17 g/cc, is

1. 36.5
2. 18.25
3. 32.05
4. 42.10

Specific volume of cylindrical virus particle is 6.02 10-2 cc/g whose radius and length are 7 A and 10 A respectively. If NA = 6.02 1023, find molecular weight of virus.

1. 15.4 kg/mol
2. 1.54 104 kg/mol
3. 3.08 104 kg/mol
4. 3.08 103 kg/mol