Laws of Definite Proportions, Multiple Proportions

Q. NaOH aqueous solution is labeled as 10% (w/v).Density of the solution is 1.02 g/ml. Then the molefraction of the solute in the solution is(1) 0.05(3) 0.53(2) 0.0466(4) 0.053

Q.

Calculate the formula mass of Zinc oxide $\left(\mathrm{ZnO}\right)$.

Given: Atomic masses of Zn = 65u, 0 = 16u

Q. Molarity of liquid HCl, if density of solution is 1.17 gm/cc is (1) 36.5 (2) 18.25 (3) 32.05 (4) 42.10

Q.

Assertion: An atom is the smallest particle in an element that has the properties of the element.

1. Both Assertion and Reason are correct and Reason is the correct explanation of Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
3. 
   Assertion is correct but Reason is incorrect.
4. Both Assertion and Reason are incorrect.

Q.

Zinc sulphate contains $22.65\%$ of zinc and $43.9\%$ of water of crystallization. If the law of constant proportions is true, then the weight of zinc required to produce 20 g of the crystals will be

1. 0.453 g
2. 453 g
3. 45.3 g
4. 4.53 g

Q. Two elements X (at mass 16) and Y (at mass 14) combine to form compounds A, B and C. The ratio of different masses of Y which combine with a fixed mass of X in A, B and C is 1 3 : 5. If 32 parts by mass of X combines with 84 parts by mass of Y in B, then in C, 16 parts by mass of X will combine with?

1. 14 parts by mass of Y
2. 42 parts by mass of Y
3. 70 parts by mass of Y
4. 84 parts by mass of Y

Q. Hydrogen combines with nitrogen in a 3:14 weight ratio to form ammonia. If every molecule of ammonia contains three atoms of hydrogen and one atom of nitrogen, an atom of nitrogen must weigh :

1. 14 times the mass of a hydrogen atom
2. 14/3 times the mass of a hydrogen atom
3. 3 times the mass of a hydrogen atom
4. 3/14 times the mass of a hydrogen atom

Q.

Assertion: An atom is the smallest particle in an element that has the properties of the element.

1. Both Assertion and Reason are correct and Reason is the correct explanation of Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion.
3. 
   Assertion is correct but Reason is incorrect.
4. Both Assertion and Reason are incorrect.

Q.

0.7 g of iron reacts directly with 0.4 g of sulphur to form ferrous sulphide. If 2.8 g f iron dissolves in dilute HCl and excess of sodium sulphide solution is added, 4.4 g of iron sulphide is precipitated. If it obeys the law of constant composition, what is the ratio of weights of Fe : S ?

1. 6:4

2. 7:4

3. 8:4

4. 4:7

Q.

An element forms two oxides of 2.9 g and 2.25 g of these oxides each was found to contain 1.12 L of $O_2$ at STP. What is the simple ratio if it obeys law of multiple proportions?

1. 3:1

2. 1:2

3. 2:1

4. 1:3

Q.

5.0 g of a certain element X forms 10.0g of its oxide having the formula $X_4{O}_6$. The atomic mass of X is ?

1. 12.0 amu

2. 24.0 amu

3. 30.0 amu

4. 32.0 amu

Q.

5.0 g of a certain element X forms 10.0g of its oxide having the formula $X_4{O}_6$. The atomic mass of X is ?

1. 24.0 amu

2. 30.0 amu

3. 32.0 amu

4. 12.0 amu

Q. Calculate the mass of urea(NH2CONH2) required in making 2.5 kg of 0.25 molal aqueous solution.

Q. Find the solubility of KNO3 at 20 degree celcius when the mass of the empty dish is 50g and solution is 65g, while the mass of dish and residue is 54.3g

Q. Irrespective of the source of water, a pure sample always yields $88.89\%$ oxygen and $11.11\%$ hydrogen by mass. This can be explained using law of

1. conservation of mass
2. definite proportions
3. multiple proportions
4. reciprocal proportions