How many grams of concentrated nitric acid solution should be used to prepare 250 mL

of 2.0M HNO₃? The concentrated acid is 70% HNO₃.

1. 45.0 g conc.HNO₃

2. 90.0 g conc.HNO₃

3. 70.0 g conc.HNO₃

4. 54.0 g conc.HNO₃

If the Avogadro number N_A, is changed from 6.022 x 10²³ mol^-1 to 6.022 x 10²⁰ mol^-1 this would change: 

1. The definition of mass in units of grams.

2. The mass of one mole of carbon.

3. The ratio of chemical species to each other in a balanced equation.

4. The ratio of elements to each other in a compound.

At standard temperature and pressure (STP), the volume of oxygen required to completely combust 30 ml of acetylene under similar conditions is:

1. 100 ml

2. 75 ml

3. 50 ml

4. 25 ml

An organic compound containing C, H, and N gave the following on analysis: C = 40%, H = 13.3% and N = 46.67%. Its empirical formula would be:

1. CHN
2. C₂H₂N
3. CH₄N
4. C₂H₇N

The number of moles of oxygen in one litre of air containing 21% oxygen by volume under standard conditions is [CBSE PMT 1995]

(1) 0.186 mole

(2) 0.21 mole

(3) 0.0093 mole

(4) 2.10 mole

The mass of carbon present in 0.5 mole of K₄[Fe(CN)₆] is:

1. 1.8 g

2. 18 g

3.  3.6 g

4.  36 g

4.4 g of an unknown gas occupies 2.24 litres of volume at NTP. The gas may be: 

At S.T.P. the density of CCl₄ vapour in g/L will be nearest to [CBSE PMT 1988]

(1) 6.84

(2) 3.42

(3) 10.26

(4) 4.57

KClO₃ on heating decomposes to KCl and O₂. The volume of O₂ at STP liberated by 0.1 mole KClO₃ is

1. 4.36 L

2. 3.36 L

3. 2.36 L

4. None of these

Oxygen contains 90% O¹⁶ and 10% O¹⁸. Its atomic mass is

(1) 17.4

(2) 16.2

(3) 16.5

(4) 17