Limitations of Chemical Reaction

Q.

Explain how digestion is an exothermic reaction. [3 MARKS]

Q.

Which of the following is the heaviest metal?

1. Silver

2. Copper

3. Gold

4. Lead

Q.

(a) What is chemical equation ?

(b) Why it is necessary to balance a chemical equation ?

(c) What are the limitation of a chemical equation ?

Q.

Why is it advised not to store pickles and curd in metallic utensils? [3 MARKS]

Q.

What is meant by the term ‘chemical equation’? What are the essentials of a chemical equation?

Q. Metals generally react with dilute acids to produce hydrogen gas. Which one of the following metals does not react with dilute hydrochloric acid?​

1. magnesium
2. aluminium
3. iron
4. copper

Q.

Why gold and silver are used to make ornaments?

1. Highly reactive
2. Highly unreactive
3. Noble gases
4. None of the above

Q. What happens when metals react with an acid

Q.

Observing the changes, in which of the following would you say a chemical reaction may be occurring?
(i) Heating iodine changes the colour from bluish black to purple
(ii) Mixing ammonia and hydrogen chloride gases gives fumes containing a white powdery substance
(iii) Mixing an acid and a base solution raises the temperature.
(iv) Mixing ferrous sulphide and hydrochloric acid gives off a gas with a rotten egg smell

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

2. (i), (ii), (iv)

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

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

Q.

End products of metallic reaction with dilute acids

Q. Question 7
Metals generally react with dilute acids to produce hydrogen gas. Which one of the following metals does not react with dilute hydrochloric acid?

(a) magnesium
(b) aluminium
(c) iron
(d) copper

Q.

Can pickles be kept in aluminium container? Explain.

Q.

Metal + Acid -

Q. How to balance a chemical reaction?

Q.

2. What prior knowledge is necessary before balancing a chemical equation?

Q. Why is respiration considered an exothermic reaction ? Explain.

1. reduction of glucose takes place
2. produces large amount of heat energy.
3. oxidation of glucose takes place
4. All of the above

Q.

How to balance chemical equation

Q. What is balancing an equation? Give detailed examples

Q. IN many chemical equation there are mixture of letters and numbers why is this so

Q.

B. Write true or false for the following statements.

(iii) The sign of arrow (→) is read as to yield or to form.

1. True
2. False

Q.

A chemical equation signifies the exact composition of the substances.

1. True
2. False

Q.

4. (a) Define word equation for a chemical reaction by giving an example.

Q.

Aerobic respiration in humans is the example of an ___ reaction.

1. Exothermic

2. Combination

3. Exothermic and combination

4. Endothermic

Q.

State the information provided by a chemical equation.

Q. Silver and gold do not react with oxygen even at a high temperature because they are highly reactive.

1. True
2. False

Q. Question 9
The metal which produces hydrogen gas on reaction with dilute hydrochloric acid as well as sodium hydroxide solution is

(a) copper
(b) iron
(c) aluminium
(d) sodium

Q.

(a) What is chemical equation ?

(b) Why it is necessary to balance a chemical equation ?

(c) What are the limitation of a chemical equation ?

Q.

$\text{CaO(s)}+{\text{H}}_2\text{O (l)}\to {\text{Ca(OH)}}_2\text{(aq)}+\text{Heat}$

What cannot be inferred from the above reaction?

1. Water $H_{2}O$ is in vapour state.
2. Calcium hydroxide ${\text{Ca(OH)}}_2$ is aqueous in nature.
3. Heat is released in the reaction.
4. Calcium oxide ($\text{CaO}$) is solid.

Q. Short cut way for balancing

Q. in gas liquid solutions change in enthalpy is always negative. why so??