A sample of pure Cu (3.18g ) heated in a stream of oxygen for some time gains in mass with the formation of black oxide of copper (CuO). The final mass is 3.92 g. The percent of copper remains unoxidised is-

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?

Versene, a chelating agent having chemical formula C₂H₄N₂(C₂H₂O₂Na)₄. If each mole of this compound could bind 1 mole of Ca²⁺, then the rating of pure versene expressed as mg of CaCO₃ bound per g of chelating agent is:

A gas is found to have the formula (CO)x. Its VD is 70. The value of x must be:

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

The molality of 1M solution of NaCl ( specific gravity 1.0585 g/mL ) is:

The total molarity of all the ions present in  0.1 M of CuSO₄ and 0.1 M of Al₂(SO₄)₃ solution is:

25 ml of a solution containing HCl and ${\mathrm{H}}_2{\mathrm{SO}}_4$ required 10 ml of a 1 N NaOH solution for neutralization. 20 ml of the same acid mixture on being treated with an excess of ${\mathrm{AgNO}}_3$ gives 0.1435 g of AgCl. The normality of HCl and normality of the ${\mathrm{H}}_2{\mathrm{SO}}_4$ are respectively

A 0.1097 gm sample of As₂O₃ require 26.10 ml of KMnO₄ solution for its titration. The molarity of KMnO₄ solution is

A sample of CaCO₃ is 50% pure. On heating 1.12 litres of CO₂ (at STP) is obtained. The weight of residues left (assuming non-volatile impurity) is -

(Ca = 40, C= 12, O=16)

Consider the given reaction,
2SO₂ + O₂ $\to$2SO₃ 
6.4 g SO₂ and 3.2 g O₂ to form SO₃ . The mass of SO₃ formed is 

The molality of a 20% (by mass) CaCO₃ solution is 
(Density of solution is 1.2 gm/ml)

1 gm butane (C₄H₁₀) is burnt with excess of O₂ to form CO₂. The approximate mass of CO₂ produced is

If 0.5 moles of BaCl₂ is reacted with 0.2 moles of Na₃PO₄ then the maximum moles of Ba₃(PO₄)₂ formed 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)

Rearrange the following (I to IV) in the order of increasing masses and choose answer from (1), (2), (3) and (4) (Atomic mass : N=14, O=16 Cu = 63)

I. 1 molecule of oxygen

II. 1 atom of nitrogen

III. 1 x 10^-10g molecule-weight of oxygen

IV. 1 x 10^-10g atom-weight of copper

What is the ratio of the number of atoms in 2.2 g of CO₂ and 1.7 g of NH₃?

How many moles of FeC₂O₄ are required to reduce one mole of KMnO₄ in acidic medium?

Which of the following pairs of gases contains the same number of molecules:-

Calculate the number of ions present in 2L of a solution of 1.6 M K₄[Fe(CN)₆]

The mass of CO₂ that shall be obtained by heating 10 kg of 80% pure lime stone (CaCO₃) is:-

How many protons are present in 1.8g of ${{\mathrm{NH}}_4}^{+}$ :-

When 1L of CO₂ is heated with graphite,the volume of the gases collected is 1.8L. What will be the number of moles of CO produced at STP?

On reduction with CO, 200 kg of iron ore (Fe₂O₃) containing 20% impurities gives iron. The amount of iron produced will be-

At STP the moles of oxygen atoms in 2.8 L of CO₂ gas is:-

Which of the following relation is incorrect:-

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?

Mass of sucrose C₁₂H₂₂O₁₁ produced by mixing 84 gm of carbon, 12gm of hydrogen and 56L. O₂ at 1atm & 273 K according to give reaction, is C(s) + H₂(g) +O₂(g) $\to$ C₁₂H₂₂O₁₁ (s)

A mixture contains Na₂CO₃ and NaHCO₃ and wt. of mixture is 10gm. Mixture on heating liberates 56ml of CO₂ at S.T.P, wt of Na₂CO₃ in mixture is

How many moles of KMnO₄ are needed to oxidize a mixture of 1 mole of each FeSO₄ & FeC₂O₄ in acidic medium