Characteristics of Chemical Reaction

Q.

Give one example of change in the substances colour during a chemical reaction.

Q. A mixture of N2 and H2 is caused to react in a closed container to form Nh3. Reaction ceases before any reactant has been totally consumed.At this stage 2 moles each of N2, H2 and Nh3 are present. Weight of N2 and H2 present originally were

Q.

Fresh milk has a pH of 6. How do you think the pH will change as it turns into curd? Explain your answer.

Q.

Is the reaction between quick lime and water endothermic or exothermic?

Q.

What are mineral acids??

Q.

What is the effect of the addition of impurities on the freezing and boiling points of a substance?

Q.

248. Reaction of acids and bases

(b) Cu(OH)₂ + HCl 🡪

Q.

What are the possible changes occur during a chemical reaction?

1. Evolution of gas

2. Change in Colour

3. Formation of Precipitate

4. A new element is formed

Q. Which one of the following can be used as a drying agent?

1. Calcium carbonate
2. Sodium Carbonate
3. Sodium bicarbonate
4. Calcium oxide

Q.

Why we write Hcl as 2HCL in the equation??

And others also like 2AL at the place of AL

Q. a Cu + b HNO3 (dil.) ------> c Cu (No3)2 + d H2O + e No.
How to solve this by algebraic method of balancing?

Q.

The new substances formed as a result of the reaction are called ________

Q.

Which of the following factor(s) influence the rate of a chemical reaction?

1. Surface area of reactants

2. Temperature

3. Catalyst

4. Concentration of reactants

Q.

How is plaster of paris obtained ? What reaction is involved in the setting of a paste of plaster of paris? What is it used for? [3 MARKS]

Q.

When carbon dioxide is passed through lime water, it turns milky due to the formation of _________.

Q. What is Valency of number and the difference when a number is written above a symbol (superscript) or below?

Q.

What is the pH of milk? How does the pH change when milk is converted into curd? Explain.

Q.

How does skeletal chemical equations differ from balanced chemical equations

Q.

Fe2O3+CO=FE+CO2 balance

Q.

The skeleton equation ___________ __________________ the relative amounts of the reactants and products.

1. Always indicate

2. Selectively indicate

3. Never indicate

4. None of the choices

Q.

Fill in the blanks :

The number of electrons lost or gained by an atom is known as --------.

Q.

Saturated solution of hydrogen chloride gas in water is called concentrated hydrochloric acid. It contains ________ by weight of hydrogen chloride.

Q. Rashi was performing an experiment. She mixed a compound X with water in a beaker. She found that the beaker was becoming hot, releasing heat and forming a new substance Y. She was shocked and left the room leaving the product. After three-four days when she returned, she found that the substance Y had changed into a shiny substance Z. What are X, Y and Z.

1. 
2. 
3. 
4. 

Q.

what is limiting reagent?

Q. The pair of compounds that cannot exist together is
(i) $FeC{l}_3,SnC{l}_2$
(ii) $HgC{l}_2,SnC{l}_2$
(iii) $FeC{l}_2,SnC{l}_2$
(iv) $FeC{l}_3,KI$

1. (i) only
2. (ii) and (iii) only
3. (i), (ii) and (iv) only
4. (iii) only

Q.

Enlist the steps to write the chemical equations.

Q. Consider the reaction: $4Al+3O_2\to 2A{l}_2{O}_3$. Each particulate-level diagram represents an initial mixture of the reactants. Each molecule represents a mole of reactants.
Which initial mixture produces the MOST product?

1. A
2. D
3. B
4. C

Q.

Neutrons are present inside the nucleus of an atom.

1. True
2. False

Q. Write the limitation of reaction given in question 2.

Q. Why does dry HCl gas not change the colour of the dry litmus paper?