Laws of Mass Conservation

Q.

What are the Limitations of the law of conservation of mass?

Q. In a chemical reaction, 300 g of a baking soda mixture containing sodium bicarbonate and vinegar on heating gave 174 g of carbon dioxide gas. How much solid residue would be left over?

1. 142 g
2. 126 g
3. 118 g
4. 104 g

Q.

0.22 g of a hydrocarbon (i.e., a compound containing carbon and hydrogen only) on complete combustion with oxygen gave 0.9 g water and 0.44 g carbon dioxide. Are these results in accordance with the law of conservation of mass (atomic mass of C = 12, H = 1, O = 16).

1. True

2. False

Q. If the law of conservation of mass was to hold true, then $20.8\text{g}$ of $BaC{l}_2$ on reaction with $9.8\text{g}$ of $H_{2}S{O}_4$ will produce $7.3\text{gm}$ of $HCl$ and what mass of $BaS{O}_4$?

1. $11.65\text{g}$
2. $23.3\text{g}$
3. $25.5\text{g}$
4. $30.6\text{g}$

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.

Show that following equations are in accordance with the law of conservation of mass:
($\mathrm{H}=1;\mathrm{Cl}=35.5$)

${\mathrm{H}}_2+{\mathrm{Cl}}_2\to 2\mathrm{HCl}$

Q. If $21\text{g}$ of $NaHC{O}_3$ is added to $15\text{g}$ of $C{H}_{3}COOH$ solution, the residue is found to weigh $25\text{g}$. what is the mass of $C{O}_2$ is released in the reaction?

1. $11\text{g}$
2. $12\text{g}$
3. $13\text{g}$
4. $10\text{g}$

Q.

Calculate the molecular mass of Ethylene (${\mathrm{C}}_2{\mathrm{H}}_4$)

Q. Calculate the mass of hydrated copper sulphate required to produce 56.90 g of the complex compound assuming other reagents to be present in excess.
$CuS{O}_4.5H_{2}O\to CuS{O}_4+5H_{2}O$
$CuS{O}_4+2KCN\to Cu(CN{)}_2+K_{2}S{O}_4$
$2Cu(CN{)}_2\to 2CuCN+(CN{)}_2$
$2CuCN+6KCN\to 2K_3\left[Cu\right(CN{)}_4]$

$(\text{Molar mass of}K=39g/mol,Cu=63.5g/mol)$

1. 122.4 g
2. 49.9 g
3. 12.24 g
4. 19.96 g

Q. 24 g of $K_{2}C{O}_3$ was treated by a series of reagents to convert all of the carbon to cyanide ions in the complex $K_{3}Z{n}_3\left[Fe\right(CN{)}_6{]}_2$. Calculate the weight of the complex formed.
(Molar mass of K = 39 g/mol, Fe = 56 g/mol, Zn = 65 g/mol)

1. 15.85 g
2. ​​​​​10.67 g
3. 6.35 g
4. 20.74 g

Q.

Balance the following chemical equation:

Fe + H₂O → Fe₃O₄ + H₂

Q.

When $20.8\mathrm{g}$ of Barium chloride is added with $14.2\mathrm{g}$ of Sodium sulphate, $23.3\mathrm{g}$ of Barium sulphate and $11.7\mathrm{g}$ of Sodium chloride are formed. Show that these observations are in agreement with the law of conservation of mass.

Q.

47 g of impure Al₂O₃ is reduced electrolytically to give aluminium and oxygen. Calculate the amount of aluminium produced.

Q. The law of conservation of mass is valid for all of the following, except:

1. Precipitation reactions
2. Nuclear reactions
3. Decomposition reactions
4. Neutralization reactions

Q.

A chemical equation is balanced according to the law of

1. Conservation of mass

2. Multiple proportions

3. Constant proportions

4. Reciprocal proportions

Q.

$3.42\mathrm{g}$ of sucrose is dissolved in $18\mathrm{g}$ water in a beaker. The number of oxygen atoms in the solution is-

1. $6.68\times {10}^{23}$

2. $6.09\times {10}^{22}$

3. $6.022\times {10}^{23}$

4. $6.68\times {10}^{21}$

Q.

Five grams of $KCl{O}_3$ yield 3.041 g of $KCl$ and 1.36 L of oxygen at standard temperature and pressure. Do these figures support the law of conservation of mass within limits of $\pm 0.4\%$ error?

1. True

2. False

Q. 1.62 g of $Ti$ reacts with an excess of $O_2$ to form $T{i}_{1.44}O$. Find the amount of the oxide formed.
(Molar mass of $Ti$ = 48 g/mol)

1. 6 g
2. 2 g
3. 4 g
4. 8 g

Q. In a chemical reaction, 300 g of a baking soda mixture containing sodium bicarbonate and vinegar on heating gave 174 g of carbon dioxide gas. How much solid residue would be left over?

1. 104 g
2. 118 g
3. 126 g
4. 142 g

Q. $S\left(s\right)+O_2\left(g\right)\to S{O}_2\left(g\right)$
$S{O}_2\left(g\right)+C{l}_2\left(g\right)+2H_{2}O\to H_{2}S{O}_4\left(l\right)+2HCl\left(l\right)$
$H_{2}S{O}_4\left(l\right)+BaC{l}_2\to BaS{O}_4\downarrow +2HCl$

112 g of sulphur is burned initially to form $S{O}_2$. Find the amount of $BaS{O}_4$ precipitate obtained in the series of reactions.
(Molar mass of Ba = 137 g/mol)

1. 815.5 g
2. 456.3 g
3. 635.7 g
4. 988.1 g

Q. 24 g of $K_{2}C{O}_3$ was treated by a series of reagents to convert all of the carbon to cyanide ions in the complex $K_{3}Z{n}_3\left[Fe\right(CN{)}_6{]}_2$. Calculate the weight of the complex formed.
(Molar mass of K = 39 g/mol, Fe = 56 g/mol, Zn = 65 g/mol)

1. 15.85 g
2. ​​​​​10.67 g
3. 6.35 g
4. 20.74 g