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The mole fraction of the solute in a 1.00 molal aqueous solution is: 

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

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 

The hydrated salt, Na₂SO₄.nH₂O, undergoes a 55% loss in mass on heating and becomes anhydrous. The value of n will be:

A partially dried clay mineral contains 8% water. The original sample contained 12% water and 45% silica. The percentage of silica  in the partially dried sample is nearly:

One mole of a mixture of CO and CO₂ requires exactly 20g of NaOH in solution for the complete conversion of all the CO₂ into Na₂CO₃. How much NaOH would it require for conversion into Na₂CO₃, if the mixture (one mole) is completely oxidised to CO₂?
1. 60g
2. 80g
3. 40g
4. 20g

When 100 mL of PH₃ is decomposed, it produces phosphorus and hydrogen. The change in volume is:

2 gm Iron pyrite (FeS₂) is burnt with O₂ to form Fe₂O₃ and SO₂. The mass of SO₂ produced is (Fe=56, S=32, O=16)
1. 2 gm
2. 2.13 gm
3. 4 gm
4. 4.26 gm

Which of the following pairs of gases contains the same number of molecules:-
(1) 16g of O₂ and 14g of N₂ 
(2) 8g of O₂ and 22g of CO₂ 
(3) 28g of N₂ and 22g of CO₂ 
(4) 32g of O₂ and 32g of N₂ 

How many moles of KMnO₄ are needed to oxidize a mixture of 1 mole of each FeSO₄ & FeC₂O₄ in acidic medium
1. $\frac{4}{5}$
2. $\frac{5}{4}$
3. $\frac{3}{4}$
4. $\frac{5}{3}$

Oxygen contains 90% O¹⁶ and 10% O¹⁸. Its atomic mass is
(1) 17.4
(2) 16.2
(3) 16.5
(4) 17

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

The number of gram molecules of oxygen in 6.02 × 10²⁴ CO molecules are:
1. 10 g molecules
2. 5 g molecules
3. 1 g molecules
4. 0.5 g molecules

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

The oxide of metal contains 40% by mass of oxygen. The percentage of chlorine in the chloride of the metal is
1. 84.7
2. 74.7
3. 64.7
4. 44.7

The empirical formula of an organic compound containing carbon and hydrogen is CH₂. The mass of one litre of this organic gas at STP  is exactly equal to that of one litre of N₂ at STP. Therefore, the molecular formula of the organic gas is:
1. C₂H₄
2. C₃H₆
3. C₆H₁₂
4. C₄H₈

A sample of pure compound is found to have Na = 0.0887 mole, O = 0.132 mole, C = 2.65 × 10²² atoms.
The empirical formula of the compound is 
(1) Na₂CO₃
(2) Na₃O₂C₅
(3) ${\mathrm{Na}}_{0.0887}{0}_{0.132}{\mathrm{C}}_{2.65\times {10}^{22}}$
(4) NaCO

Volume occupied by one molecule of water (density = 1g cm^-3) is:
1. 9.0 x 10^-23 cm³
2. 6.023 x 10^-23 cm³
3. 3.0 x10^-23 cm³
4. 5.5 x10^-23 cm³

A mixture of methane and ethene in the molar ratio of x : y has a mean molar mass of 20. What would be the mean molar mass. if the gases are mixed in the molar ratio of y : x?
(1) 22                               
(2) 24
(3) 20.8                           
(4) 19

A sample of phosphorus that weights 12.4 g exerts a pressure 8 atm in a 0.821 litre closed vessel at 527$°$C. The molecular formula of the phosphorus vapour is:
1.  ${\mathrm{P}}_2$
2.  ${\mathrm{P}}_4$
3.  ${\mathrm{P}}_6$
4.  ${\mathrm{P}}_8$

What volume of HCl solution of density 1.2 g/cm³ and containing 36.5% by weight HCl, must be allowed to react with zinc(Zn) in order to liberate 4.0 g of hydrogen?
1.  333.33 mL
2.  500 mL
3.  614.66 mL
4.  None of these

The molar mass of diacidic organic Lewis base (B), if 12 g of chloroplatinate salt $\left({\mathrm{BH}}_2{\mathrm{PtCl}}_6\right)$ on ignition produced 5 gm residue of Pt,will be -
1.  52
2.  58
3.  88
4.  None of these

Equivalent weight of ${\mathrm{FeS}}_2$ in the half reaction, ${\mathrm{FeS}}_2 \stackrel{}{\to } {\mathrm{Fe}}_2{\mathrm{O}}_3+{\mathrm{SO}}_2$ is:
1.  M/10
2.  M/11
3.  M/6
4.  M/1

The equivalent weight of $\mathrm{HCl}$ in the given reaction is: ${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7+14\mathrm{HCl} \to 2\mathrm{KCl}+2{\mathrm{CrCl}}_3+3{\mathrm{Cl}}_2+{\mathrm{H}}_2\mathrm{O}$
1.  16.25
2.  36.5
3.  73
4.  85.1

Equivalent weight of ${\mathrm{H}}_3{\mathrm{PO}}_2$ when it disproportionate into ${\mathrm{PH}}_3$ and ${\mathrm{H}}_3{\mathrm{PO}}_3$ is:
1. M
2. M/2
3. M/4
4. 3M/4

In preparation of iron from haematite $\left(F{e}_2{O}_3\right)$by the reaction with carbon:
                          $F{e}_2{O}_3 + C \to Fe + C{O}_2$
How much 80% pure iron could be produced from 120 kg of 90% pure $F{e}_2{O}_3$?
1. 94.5 kg
2. 60.48 kg
3. 116.66 kg
4. 120 kg