Chemistry

Q.

A solution of a substance X is used for white washing. Name the substance X and write its formula. Write the reaction of the substance X named in above with water.

Q.

Barium chloride $+$Aluminium sulfate$\to$Barium sulfate$+$Aluminum chloride. Write the balanced equation for the above chemical reactions.

Q.

Why should a magnesium ribbon be cleaned before burning in air?

Q.

Write a balanced equation for Aluminium + Copper chloride → Aluminium chloride + copper.

Q.

Write one equation each for decomposition reactions where energy is supplied in the form of heat, light, or electricity.

Q. What do you mean by a precipitation reaction? Explain by giving examples.

Q.

Write the balanced equation for the following chemical reactions.

(a) Hydrogen + Chlorine → Hydrogen chloride

Q.

Write a balanced chemical equation with state symbols for the following reaction:

(ii) Sodium hydroxide solution in water reacts with a hydrochloric acid solution to produce Sodium chloride solution and water.

Q.

Write balanced chemical equations for the following reactions:

$\mathrm{Zinc}+\mathrm{Silver}\mathrm{nitrate}\to \mathrm{Zinc}\mathrm{nitrate}+\mathrm{Silver}$

Q.

The number of atoms present in 4.25 g of $\left({\mathrm{NH}}_3\right)$ is approximately.

a) $1\times {10}^{23}$

b) $1.5\times {10}^{23}$

c) $0.25\times {10}^{23}$

d) $6.02\times {10}^{23}$

Q. Question 3.1

Write a balanced chemical equation with state symbols for the reaction:

The solution of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.

Q.

Balance the following chemical equation

Calcium hydroxide + carbon dioxide -calcium carbonate + water

Q. Question 2

Why is the amount of gas collected in one of the test tubes in Activity 1.7 double of the amount collected in the other? Name this gas.

Q.

Write the balanced equation for the following chemical reactions: Sodium + Water → Sodium hydroxide + Hydrogen

Q. Question 5.2
Translate the following statement into chemical equation and then balance it:

Hydrogen sulphide gas burns in air to give water and sulphur dioxide.

Q.

Why are decomposition reactions called the opposite of combination reactions? Write equations for this reaction.

Q.

Balance this equation: $\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\to \mathrm{PbO}+{\mathrm{NO}}_2+{\mathrm{O}}_2$

Q.

How can we find in which period and group in periodic table a element exist. Explain whole method thoroughly?

Q. Why does iron nail become brownish in color when immersed in copper sulphate solution and and the blue color of the solution fade?

Q. Question 3
Why does our palm feel cold when we put some acetone or petrol or perfume on it?

Q. Question 9
What does one mean by exothermic and endothermic reactions? Give examples.

Q. Lead nitrate on thermal decomposition produces:

1. Lead oxide
2. Nitrogen dioxide
3. Nitrogen trioxide
4. Carbon dioxide

Q.

Sodium reacts with water to give sodium hydroxide and hydrogen. Write a balanced chemical equation for this reaction.

Q.

What is double displacement reaction. Give an example.

Q.

Give an example of a reaction in which colour change is accompanied.

Q.

Balance the following chemical reaction:

${\mathrm{MnO}}_2+\mathrm{HCl}\to {\mathrm{MnCl}}_2+{\mathrm{H}}_2\mathrm{O}+{\mathrm{Cl}}_2$

Q.

Why should magnesium ribbon be cleaned before burning in air?

Q.

The formula to calculate the rate of the reaction in terms of concentration of reactants is

1. $\text{Rate of reaction}=\frac{\text{Amount of reactant used}}{\text{Time taken for the consumption of the reactant}}$

2. $\text{Rate of reaction = Amount of reactant used}\times \text{Time taken for the consumption of the reactant}$

3. $\text{Rate of reaction = Amount of reactant used - Time taken for the consumption of the reactant}$

4. $\text{Rate of reaction = Amount of reactant used + Time taken for the consumption of the reactant}$

Q.

Calculate the molecular mass of ${\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}$.

Q.

Balance the equation ${\mathrm{BaCl}}_2+{\mathrm{H}}_2{\mathrm{SO}}_4\to {\mathrm{BaSO}}_4+\mathrm{HCl}$