Laws of Chemical Combination

Q. Complete combustion of 750 g of an organic compound provides 420 g of $C{O}_2$ and 210 g of $H_{2}O$.The percentage composition of carbon and hydrogen in organic compound is 15.3 and respectively.
(Rounded off to the nearest integer)

Q. Carbon is found to form two oxides which contain 42.9% and 27.3% of carbon respectively. The above data supports:

1. Law of constant proportion
2. Law of multiple proportion
3. Law of reciprocal proportion
4. None of these

Q.

Glucose $\left({\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\right)$ contains ______ percentage of carbon by weight.

Q.

Calculate the percentage composition of nitrogen in urea.

Q.

The substance $A$ when dissolved in solvent $B$ shows the molecular mass corresponding to $A_3$. What is the Vant Hoffs factor?

Q. Which one of the following combinations illustrate the law of reciprocal proportions?

1. $N_2{O}_3,N_2{O}_4,N_2{O}_5$
2. $NaCl,NaBr,NaI$
3. $C{S}_2,C{O}_2,S{O}_2$
4. $P{H}_3,P_2{O}_3,P_2{O}_5$

Q.

Calculate the percentage composition of chromium in potassium dichromate?

Q.

Which chapter we have to do first Atomic structure or Mole concept?

Q. Complete combustion of $1.80g$ of an oxygen containing compound $\left(C_x{H}_y{O}_z\right)$ gave $2.64g$ of $C{O}_2$ and $1.08g$ of $H_{2}O$. The percentage of oxygen in the organic compound is:

1. 50.33
2. 53.33
3. 51.63
4. 63.53

Q.

Daltons atomic theory successfully explained

(i) Law of conservation of mass

(ii) Law of constant composition

(iii) Law of radioactivity

(iv) Law of multiple proportions

1. (i), (ii) and (iii)

2. (i), (iii) and (iv)

3. (ii), (iii) and (iv)

4. (i), (ii) and (iv)

Q. Which of the following is not in accordance with Dalton’s atomic theory?

1. Matter is made up of extremely small indivisible particles called atoms.
2. Atoms can neither be created nor be destroyed in a chemical reaction.
3. Atoms of different elements may combine with each other in a fixed, simple, whole number ratio to form compounds.
4. Equal volume of all gases under similar conditions of temperature and pressure contain different number of molecules.

Q. What is the volume ratio of the product gases obtained from the decomposition of phosphorous pentachloride?
$PC{l}_5\text{(g)}\to PC{l}_3\text{(g)}+C{l}_2\text{(g)}$

1. $2:1$
2. $1:2$
3. $1:1$
4. $1:3$

Q.

Question 22

One of the statements of Dalton's atomic theory is given below "Compounds are formed when atoms of different elements combine in a fixed ratio"

(a) Law of conservation of mass (b) Law of definite proportions

(c) Law of multiple proportions (d) Avogadro law

Q. Which of the following statements represents Avogadro’s hypothesis?

1. Equal volumes of all gases under the same conditions of temperature and pressure contain an equal number of particles
2. Atoms of different elements may combine with each other in a fixed, simple, whole number ratio to form compounds
3. Gases react together in volumes which bear a simple ratio to one another
4. Equal volumes of all gases under the same temperature and pressure conditions contain an equal number of atoms

Q. Q) When a mixture of 10 moles of SO2 and 15 moles of O2 was passed over catalyst, 8 moles of SO3 were formed. How many moles of SO2 and O2 did not enter combination respectively?

Q.

The foundation for the law of chemical combination was laid by:

1. Dalton

2. Proust

3. Democritus

4. Lavoisier

Q. What is the volume ratio of the product gases obtained from the decomposition of phosphorous pentachloride?
$PC{l}_5\text{(g)}\to PC{l}_3\text{(g)}+C{l}_2\text{(g)}$

1. $2:1$
2. $1:2$
3. $1:1$
4. $1:3$

Q. Match the following, choosing one item from Column - X and the appropriate related item from Column - Y.
$\begin{array}{cc}\text{Column-X}& \text{Column-Y}\\ \begin{array}{cc}\text{(p)}& \text{Equal volumes of all gases contain}\\ & \text{equal number of molecules at NTP.}\end{array}& \text{(i) Dalton's atomic theory}\\ \begin{array}{cc}\text{(q)}& \text{The atom is indestructible}\end{array}& \text{(ii) Law of conservation of mass}\\ \begin{array}{cc}\text{(r)}& \text{All pure samples of the compound}\\ & \text{contain the same elements combined}\\ & \text{in the same proportion of mass.}\end{array}& \text{(iii) Avogadro's law}\\ \begin{array}{cc}\text{(s)}& \text{Total mass before and after the}\\ & \text{chemical reaction is same.}\end{array}& \text{(iv) Gay-Lussac's law}\\ \begin{array}{cc}\text{(t)}& \text{Gases react in simple ratio of their}\\ & \text{volumes}\end{array}& \text{(v) Law of constant proportions}\end{array}$

1. (p – iii), (q – i), (r – v), (s – iv), (t – ii)
2. (p – iii), (q – v), (r – i), (s – ii), (t – iv)
3. (p – iii), (q – i), (r – v), (s – ii), (t – iv)
4. (p – iii), (q – ii), (r – v), (s – i), (t – iv)

Q.

Write the chemical formulas for washing soda and baking soda, and calculate the percentage of sodium by weight in each of the two.

Q. Sodium and oxygen combine to form two compounds of which one is $N{a}_{2}O$. The percentage of sodium in the other compound is 59%. Calculate the molecular weight of the compound.

1. 42
2. 78
3. 62
4. 108

Q. A mixture of $FeO$ and $F{e}_3{O}_4$ when heated in air to constant weight gains $5\%$ in its weight. The $\%$ of $FeO$ in the sample is:

1. $20.25\%$
2. $79.75\%$
3. $35.75\%$
4. $64.25\%$

Q.

Fill in the blanks with suitable words :

Helium is stabilised by the law of ---------

Q. An organic compound contains $C,H$ and $S$. The minimum molecular weight of the compound containing $8\%$ sulphur is:

1. $200g$ $mo{l}^{-1}$
2. $400g$ $mo{l}^{-1}$
3. $300g$ $mo{l}^{-1}$
4. $600g$ $mo{l}^{-1}$

Q.

How does Avogadros law explain Gay-Lussacs law of combining volumes?

Q. In a polymer sample $30\%$ of molecules have a molecular mass of $20,000$, $40\%$ have $30,000$ and the rest $60,000$. What is the weight average molecular mass of the polymer?

1. $40,300$
2. $43,333$
3. $50,400$
4. $30,600$

Q. The half-life of radium is about 1600 years. Out of 100g of radium existing now, 25g will remain undecayed after:

1. 6400 years
2. 2400 years
3. 3200 years
4. 4800 years

Q. Who gave the four laws of chemical combination?

Q. Carbon is found to form two oxides which contain 42.9% and 27.3% of carbon respectively. The above data supports:

1. Law of constant proportion
2. Law of multiple proportion
3. Law of reciprocal proportion
4. None of these

Q. Calculate the % composition of Carbon in $C{O}_2$. Molar mass is 44.01.

1. 40%
2. 67%
3. 30%
4. 27%

Q. Rearrange the following in the order of increasing mass and choose the correct order (Atomic mass, $N=14,O=16,Cu=63$)
(I) 1 molecule of oxygen
(2) 1 atom of nitrogen
(3) $1\times {10}^{-10}gm$ molecule of oxygen
(4) $1\times {10}^{-10}gm$ of copper

1. $II<I<IV<III$
2. $IV<III<II<I$
3. $II<III<I<IV$
4. $III<IV<I<II$