Metallic Oxides

Q.

When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.

Q.

Why is burning of paper a chemical change?

Q.

When a magnesium ribbon is burnt in the air, the ash formed is

1. Black

2. White

3. Yellow

4. Pink

Q. Burning of magnesium ribbon is a ________ change.

1. permanent and reversible
2. temporary and reversible
3. temporary and irreversible
4. permanent and irreversible

Q.

What is the weight Of ${\mathrm{V}}_2{\mathrm{O}}_5$ produced from $2g$of $\mathrm{VO}$ and $5.75g$ of ${\mathrm{Fe}}_2{\mathrm{O}}_3$?

1. $5.07g$

2. $5.17g$

3. $5.27g$

4. $5.37g$

Q.

(a) What happens when baking soda is added to lemon juice?
(b) Is digestion a chemical change?
[3 MARKS]

Q.

Burning of fuel is a ___________ (physical/chemical) change.

Q. Question 3
Magnesium ribbon on burning in air produces

(a) magnesium oxide, water and light
(b) magnesium oxide and heat
(c) magnesium oxide, heat and light
(d) magnesium oxide, water and heat

Q.

What is the percentage composition of ammonium nitrate, ${\mathrm{NH}}_4{\mathrm{NO}}_3$?

Q. When magnesium ribbon burns in the air, it forms white ash. The chemical name of white ash is:

1. Magnesium dioxide
2. Milk of magnesia
3. Magnesium oxide
4. Magnesium hydride

Q. (a) Condensation of steam is not a chemical change. Explain.

(b) If two liquids are immiscible, which of the two liquids will be at the bottom if they are taken together in a container?
[2 MARKS]

Q.

Magnesium$\left(\mathrm{Mg}\right)$ reacts with steam to form --------------- and Hydrogen$\left({\mathrm{H}}_2\right)$ gas.

Q. The burning of a piece of magnesium ribbon in air is a chemical change. Explain.

Q.

With the help of an activity, show that burning of paper is a chemical change.

Q.

When a chemical change takes place in matter, we commonly say a chemical reaction takes place

1. True
2. False

Q. Give four reasons why burning of a magnesium ribbon in air is considered a chemical change.

Q.

Define burning. What type of change is it?${\mathrm{CO}}_2$

Q.

Pavani is a very mischievous girl, she added baking soda in lemon juice. As soon as baking soda was added in lemon juice some changes took place and she was stunned, what kind of changes happened?. Explain briefly. [3 MARKS]

Q.

A reaction in which chemical change takes place is called a chemical reaction.

1. True
2. False

Q. The explosion of fireworks is an example of __________ change.

1. physical
2. chemical
3. temporary
4. natural

Q.

The burning of magnesium ribbon is an irreversible change.

1. True
2. False

Q. When a magnesium ribbon burns in air, the ash formed is dissolved in water:

1. the solution of ash in water is basic in nature
2. the solution of ash in water is acidic in nature
   
3. the solution of ash in water is neutral in nature
   
4. none of these

Q.

What do you observe when:

Burning magnesium wire is introduced in a jar of carbon dioxide.

Q.

Which of the following does not involve a chemical reaction?

1. digestion of food in our body

2. process of respiration

3. burning of candle wax when heated

4. melting of candle wax on heating

Q.

By giving a reason state why chemical change takes place in the following case:

Burning of wood.

Q. $2Mg+O_2⟶$

1. $MgO$
2. $2MgO$
3. $Mg{O}_2$
4. $2Mg{O}_2$

Q.

What is a chemical change? Give two examples.

Q. The explosion of fireworks is an example of __________ change.

1. physical
2. chemical
3. temporary
4. natural

Q.

The teacher asked the class" give one example of irreversible reaction" ..Four student raised their hands. Figure out the right answer.

1. Arvind: " sublimation of camphor "

2. Harish: " Dissolution of salt in water"

3. Prema: " Burning of paper"

4. Lata: " Heating Zinc Oxide "

Q.

Suppose you have to determine the percentage of carbon dioxide in a sample of a gas available in a container. Which is the best absorbing material that can be used to retrieve carbon dioxide.

1. Cold, solid calcium chloride

2. Cold, solid calcium hydroxide

3. Heated copper oxide

4. Heated charcoal