Laws of Chemical Combination

Q. Which of the following sets of compounds correctly illustrates the law of reciprocal proportions?

1. $P_2{O}_5,P{H}_3,H_{2}O$
2. $P_2{O}_3,P{H}_3,H_{2}O$
3. $N_{2}O,N{H}_3,H_{2}O$
4. $N_2{O}_5,N{H}_3,H_{2}O$

Q. Arrange the following in order of increasing mass
(i) $3.0115\times {10}^{23}$ molecules of white phosphorus $\left(P_4\right)$
(ii) $10$ moles of $H_2$ gas
(iii) $1g$ molecule of anhydrous $N{a}_{2}C{O}_3$
(iv) $33.6L$ of $C{O}_2$ gas at S.T.P

1. $ii<i<iv<iii$
2. $iii<vi<i<ii$
3. $i<ii<iv<iii$
4. $i<iv<iii<ii$

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 (u) of the compound.

Q. When 0.0976 g of magnesium was heated in air, 0.1627 g of magnesium oxide $\left(MgO\right)$ was produced. What is the mass of oxygen needed to produce 0.1627 g of $MgO$?

1. 0.0651 g
2. 0.0561 g
3. 0.0115 g
4. 0.6051 g

Q. Which of the following sets of compounds correctly illustrates the law of reciprocal proportions?

1. $P_2{O}_3,P{H}_3,H_{2}O$
2. $P_2{O}_5,P{H}_3,H_{2}O$
3. $N_2{O}_5,N{H}_3,H_{2}O$
4. $N_{2}O,N{H}_3,H_{2}O$

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 of different elements may combine with each other in a fixed, simple, whole number ratio to form compounds.
3. Atoms can neither be created nor be destroyed in a chemical reaction.
4. Equal volume of all gases under similar conditions of temperature and pressure contain different number of molecules.

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

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

Q. A 19.6 g of a given gaseous sample contains 2.8 g of molecules $d=0.75g{L}^{-1}$ 11.2 g of molecules $(d=3g{L}^{-1})$ and 5.6 g of molecules $(d=1.5g{L}^{-1})$. All density measurements are made at STP. Calculate the total number of molecules (N) present in the given sample. Report your answer in $N\times {10}^{23}$.
Assume Avogardro's number as $6\times {10}^{23}$.

1. 3
2. 2
3. 2.5
4. 4

Q. 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.” Which of the following laws is not related to this statement?

1. Law of conservation of mass
2. Law of definite proportions
3. Law of multiple proportions
4. None of these

Q. When $x$ g of $NaHC{O}_3$ is heated, 12.62 g of $N{a}_{2}C{O}_3$, 5.24 g of $C{O}_2$ and 2.14 g of $H_{2}O$ were produced. What is $x$?

1. 20.00 g
2. 15.00 g
3. 
   17.86 g
4. 12.64 g

Q. When $10g$ of $KHC{O}_3$ is heated, $6.31g$ of $K_{2}C{O}_3$ and $1.07g$ of $H_{2}O$ are produced. How many grams of $C{O}_2$ will be produced?

1. $2.14g$
2. $1.07g$
3. $2.62g$
4. $1.14g$

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. When 0.0976 g of magnesium was heated in air, 0.1627 g of magnesium oxide $\left(MgO\right)$ was produced. What is the mass of oxygen needed to produce 0.1627 g of $MgO$?

1. 0.0651 g
2. 0.0561 g
3. 0.0115 g
4. 0.6051 g

Q. When $10g$ of $KHC{O}_3$ is heated, $6.31g$ of $K_{2}C{O}_3$ and $1.07g$ of $H_{2}O$ are produced. How many grams of $C{O}_2$ will be produced?

1. $2.14g$
2. $1.07g$
3. $2.62g$
4. $1.14g$

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:(Give your answer upto one decimal only)

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