# Stoichiometry

### How many moles of magnesium phosphate

How many moles of magnesium phosphate, Mg3(PO4)2 will contain 0.25 mole of oxygen atoms?

1. 2.5 x 10-2
2. 0.02
3. 1.25 x 10-2
4. 3.125 x 10-2

### If we consider that 1/6, in place of 1/12, mass of carbon atom

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

1. decrease twice
2. remain unchanged
3. increase two fold
4. be a function of the molecular mass of the substance

### With increase of temperature, which of these changes

With increase of temperature, which of these changes?

1. molality
2. molarity
3. mole fraction
4. weight fraction of solute

### What volume of hydrogen gas, at 273 K and 1 atm

What volume of hydrogen gas, at 273 K and 1 atm. pressure will be consumed in obtaining 21.6 g of elemental boron (atomic mass = 10.8) from the reduction of boron trichloride by hydrogen?

1. 89.6 L
2. 67.2 L
3. 44.8 L
4. 22.4 L

### Number of atoms in 558.5 gram Fe

Number of atoms in 558.5 gram Fe (atomic weight of Fe = 55.85 g mol–1) is

1. twice that in 60 g carbon
2. 558.5 × 6.023 × 1023
3. half that in 8 g He
4. 6.023 × 1022

### In the reaction, 2Al (s) + 6HCl (aq)

In the reaction,

2Al (s) + 6HCl (aq) → 2Al3+ (aq) + 6Cl (aq) + 3H2 (g)

1. 6 L HCl (aq) is consumed for every 3 L H2(g) produced
2. 11.2 L H2(g) at STP is produced for every mole HCl (aq) consumed
3. 33.6 L H2(g) is produced regardless of temperature and pressure for every mole Al that reacts
4. 67.2 L H2(g) at STP is produced for every mole Al that reacts

### The molecular formula of a commercial resin used for exchanging ions

The molecular formula of a commercial resin used for exchanging ions in water softening is C8H7SO3Na (Mol. Wt. 206). What would be the maximum uptake of Ca2+ ions by the resin when expressed in mole per gram resin?

1. 2/309
2. 1/103
3. 1/206
4. 1/412

### In a compound C, H and N atoms are present in 9:1:3.5 by weight

In a compound C, H and N atoms are present in 9:1:3.5 by weight. Molecular weight of compound is 108. Molecular formula of compound is

1. C9H12N3
2. C3H4N
3. C6H8N2
4. C2H6N2

### A sample of a hydrate of barium chloride weighing 61 g was heated until all the water of hydration is removed

A sample of a hydrate of barium chloride weighing 61 g was heated until all the water of hydration is removed. The dried sample weighed 52 g. The formula of the hydrated salt is: (atomic mass, Ba = 137 amu, Cl = 35.5 amu)

1. BaCl2.H2O
2. BaCl2.2H2O
3. BaCl2.3H2O
4. BaCl2.4H2O