Need for Balancing

Q.

Is the equation $\mathrm{Mg}+\mathrm{HCl}\to {\mathrm{MgCl}}_2+{\mathrm{H}}_2$ balanced or not?

Q.

Is the ice melting endothermic or exothermic?

Q.

How can you balance a chemical equation by the hit and trial method? Explain with an example.

Q.

How to balance the equation by shortcut method?

Q.

What is Landolts experiment?

Q. If the masses of Cr and O are in ratio 13:12 in CrO3 then the ratio if O that combinrs with the same mass of Cr in Cr2O3 and Cr2 O7 is ?

Q.

Which observation does not indicate that a chemical reaction has occurred?

1. Formation of a precipitate
2. Production of gas.
3. Evolution of heat and light.
4. Change in total mass of substance

Q.

Show that the reaction of ammonia and hydrochloric acid to form ammonium chloride is in accordance with the law of conservation of mass. $(\mathrm{N}=14,\mathrm{Cl}=35.5,\mathrm{H}=1)$
${\mathrm{NH}}_3+\mathrm{HCl}\rightleftharpoons {\mathrm{NH}}_4\mathrm{Cl}$

Q.

Differentiate between :

(a) Reactants and products.

(b) A balanced and an unnbalanced chemical equation.

Q. How to write chemical formulas?

Q.

State the law of conversion of mass.

Q.

During interconversion of matter, mass remains constant.

1. True
2. False

Q.

Mass of products is equal to mass of reactants. Give reason?

Q.

According to the law of conservation of mass, ___________ can neither be created nor destroyed in a chemical reaction.

Q.

The law of conservation of mass states that mass is created during a chemical reaction.

1. True
2. False

Q.

Write the following in the form of a word equation:

$2NaOH+CaB{r}_2\to Ca(OH{)}_2+2NaBr$

In the formula $CaB{r}_2$ what does $Ca$ stand for and what is its valency?

1. Sodium Hydroxide + Calcium bromide $\to$ Calcium hydroxide + Sodium bromide; potassium; 2

2. Sodium hydroxide + Calcium bromide $\to$ Calcium hydroxide + Sodium bromide; calcium; 2

3. Sodium hydroxide + Calcium bromide $\leftrightarrow$ Calcium hydroxide + Sodium bromide; calcium; 2

4. Sodium hydroxide + Calcium bromide = Calcium hydroxide + Sodium bromide; calcium; 1

Q.

Raghav was performing an experiment in which he combined 0.5 g of ammonia with 1.1 g of HCl to produce ammonium chloride. Again he reacted the ammonium chloride produced with 5.2 g of silver nitrate and formed X g of ammonium nitrate and 4.4 g of silver chloride precipitates out. Find the value of X.

1. 1.2 gm

2. 10.8 gm

3. 11.2 gm

4. 9.8 gm

Q.

Describe a chemical equation with an example.

Q.

As a car runs out of petrol, what happens to petrol?

1. It has been converted into other compounds.

2. It has been destroyed.

3. It has vapourized.

4. None of the above

Q.

What is meant by the terms skeleton equation?

Q.

Consider the following reaction.

$Cu(N{O}_3{)}_2\to CuO+N{O}_2+O_2$
Which of the following statement is correct?

1. Number of atoms on either side of the reaction are equal

2. Mass of reactants is not equal to mass of products

3. Number of atoms on product side is more than the reactant side

4. Mass of products = mass of reactants

Q.

Complete the following equation and balance.

$\mathrm{AgCl}\left(\mathrm{s}\right)\stackrel{\mathrm{Light}}{\to }\mathrm{Ag}\left(\mathrm{s}\right)+\mathrm{\_\_\_\_\_\_\_\_\_\_}$

Q.

The substance that takes part in a chemical reaction.

1. Reactant

2. Product

3. Element

4. None of these

Q.

Consider the following reaction.

$Cu(N{O}_3{)}_2\to CuO+N{O}_2+O_2$ Which of the following statement is correct?

1. Mass of products = mass of reactants

2. Mass of reactants is not equal to mass of products

3. Number of atoms on either side of the reaction are equal

4. Number of atoms on product side is more than the reactant side

Q.

Differentiate between :

(a) Reactants and products.

(b) A balanced and an unnbalanced chemical equation.

Q.

Raghav performed an experiment in which he combined 0.5 g of ammonia with 1.1 g of HCl to produce ammonium chloride. Again, he reacted the ammonium chloride produced with 5.2 g of silver nitrate and formed X g of ammonium nitrate and 4 g of silver chloride precipitates out. Find the value of X.

1. 10.8 gm

2. 11.2 gm

3. 9.8 gm

4. 1.2 gm

Q. Write the following in the form of a word equation:
Sodium hydroxide reacts with calcium bromide to form calcium hydroxide and sodium bromide.In the formula $CaB{r}_2$​ what does Ca stand for and what is its valency?

1. Sodium hydroxide + calcium bromide $\leftrightarrow$ Calcium hydroxide + sodium bromide; calcium; 3
2. Sodium hydroxide + calcium bromide $\to$ Calcium hydroxide + sodium bromide; potassium; 2
3. Sodium hydroxide + calcium bromide = Calcium hydroxide + sodium bromide; calcium; 1
4. Sodium hydroxide + calcium bromide $\to$ Calcium hydroxide + sodium bromide; calcium; 2

Q.

Identify the monoatomic and polyatomic ions from the following equation-
$Pb(N{O}_3{)}_2$ + $K_{2}S{O}_4$ $\to$ $2KN{O}_3$ + $PbS{O}_4$

1. Sodium hydroxide + calcium bromide = Calcium hydroxide + sodium bromide; calcium; 1

2. Sodium hydroxide + calcium bromide $\to$ Calcium hydroxide + sodium bromide; calcium; 2

3. Sodium hydroxide + calcium bromide $\to$ Calcium hydroxide + sodium bromide; potassium; 2

4. Sodium hydroxide + calcium bromide $\leftrightarrow$ Calcium hydroxide + sodium bromide; calcium; 2

Q.

An unbalanced chemical equation is also known as:

1. Skeletal equation

2. Proper equation

3. Unorganised equation

4. Word equation

Q.

X and Y chemically react to form a new product Z.

X+Y→Z

The masses of X and Y are 5 g and 6 g respectively. The mass of Z is ___ g.

1. 6

2. 5

3. 10
4. 11