Which of The following has a maximum number of molecules?

1. 7g N₂ 

2. 2g H₂ 

3. 16g NO₂ 

4. 16g O₂ 

Calculate the number of moles of oxygen in 1L of air containing 21% oxygen by volume, under standard conditions.

1. 0.0093 mole

2. 2.10 moles

3. 0.186 mole

4. 0.21 mole

How much oxygen gas (O₂) at standard temperature (0°C) and pressure (1 atm) is required to completely combust 1 liter of propane gas (C₃H₈) under the same conditions?

1 g of magnesium is burnt with 0.56g of oxygen in a closed vessel. The left-out reactant and its quantity are

(At. weight of Mg = 24, O=16)

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

1. 1.568 x 10³ 

2. 15.68

3. 2.168 x 10⁴ 

4. 1.568 x 10⁴ 

The total number of valence electrons in 4.2g of ${\mathrm{N}}_3^{-}$ ion is (N_A is the Avogadro's number)

1. 2.1N_A 

2. 4.2N_A 

3. 1.6N_A 

4. 3.2N_A 

When 22.4L of H₂(g) is mixed with 11.2L of Cl₂(g) each at STP, the moles of HCl(g) formed is equal to 

1. 1 mole of HCl(g)

2. 2 moles of HCl(g)

3. 0.5 mole of HCl(g)

4. 1.5 moles of  HCl(g)

The mass of carbon anode consumed (giving only carbon dioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (at. mass of Al = 27)

1. 180 kg

2. 270 kg

3. 540 kg

4. 90 kg

In the Haber process, 30 L of dihydrogen and 30 L of dinitrogen were taken for the reaction, which yielded only 50% of the expected product. The composition of the gaseous mixture under the said conditions at the end is: 

1. 20 L ammonia, 10 L nitrogen, 30 L hydrogen

2. 20 L ammonia, 25 L nitrogen, 15 L hydrogen

3. 20 L ammonia, 20 L nitrogen, 20 L hydrogen

4. 10 L ammonia, 25 L nitrogen, 15 L hydrogen

What is the approximate number of atoms present in 4.25 grams of NH₃?

1. 4 x 10²³ 

2. 2 x 10²³ 

3. 1 x 10²³ 

4. 6 x 10²³