Basic Oxides of Metals

Q.

A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.

(a) Why do silver articles turn black when kept in the open for a few days? Name the phenomenon involved.

(b) Name the black substance formed and give its chemical formula.

Q.

Write a word equation for the reaction of magnesium with oxygen.

Q.

Classify Following Oxides As Neutral, Acidic, Basic Or Amphoteric: $\mathrm{CO},{\mathrm{B}}_2{\mathrm{O}}_3,{\mathrm{SiO}}_2,{\mathrm{CO}}_2,{\mathrm{Al}}_2{\mathrm{O}}_3,{\mathrm{PbO}}_2,\mathrm{Tl}2{\mathrm{O}}_3.$

Q.

On immersing an iron nail in CuSO₄ solution for a few minutes, you will observe

1. No reaction takes place

2. The colour of the solution fades away

3. The surface of iron nails acquires a black coating

4. The colour of the solution changes to green

Q. Metal oxides are basic in nature.

1. False
2. True

Q.

Magnesium reacts with cold water to form magnesium oxide and hydrogen gas.

1. True
2. False

Q.

What is the nature (acidic /basic) of the following oxides ?

(a) Magnesium oxide (b) Sulphur dioxide

Give reason for your choice.

Q.

When a copper object is exposed to moist air for a long time, then a green coating is formed on its surface.

(a) What is the material of the green coating ?

(b) State whether the green coating is acidic or basic.

Q.

Metallic oxides are also known as _______ oxides.

Q.

The element Z burns in air to form an oxide.The aqueous solution of this oxide turns blue litmus to red.

(a) carbon

(b) calcium

(c) iron

(d) magnesium

Q.

Write the names of two neutral oxides.

Q.

(a) What happens when sulphur dioxide is dissolved in water ? Write a word equation for the reaction which takes place.

(b) What happens when an iron nail is placed in copper sulphate solution ? Write word equation of the reaction involved.

Q. force holds the electrons and protons together.

1. Gravitational
2. Electrostatic
3. Repulsive

Q.

Common name of lead oxide is.

Q.

Rust is iron oxide.Will it be acidic or basic?

Why?

Q.

An element forms an oxide which is basic in nature.State whether the element is a metal or non-metal ?

Q. When magnesium ribbon is burnt in air, the ash formed is ________ in nature.

1. acidic
2. basic
3. neutral
4. amphoteric

Q.

When a vessel is exposed to moist air for a long time, then a green coating is formed on its surface.The vessel must be made of :

(a) zinc

(b) magnesium

(c) iron

(d) copper

Q.

The solution obtained on dissolving magnesium oxide in water is basic in nature.

1. True

2. False

Q.

The element whose oxide will turn red litmus solution to blue will be:

(a) sodium

(b) sulphur

(c) carbon

(d) sonorousness

Q. Which of the following gas helps in combustion process?

1. Hydrogen
2. Nitrogen
3. Oxygen
4. Argon

Q. The addition of hydrogen to or the removal of oxygen from a substance is called _____.

1. oxidation
2. reduction
3. redox
4. displacement reaction

Q. In the reaction given below, 'M' is an alkali metal which reacts with oxygen and gives X. Select a suitable option pertaining to the nature of product X.
$\text{M}+{\text{O}}_2\to \text{X}$

1. Basic oxide
2. Neutral oxide
3. Acidic oxide
4. Amphoteric oxide

Q.

What are oxides ? Give two examples of each of the following oxides.

(a) Basis oxide (b) Acidic oxide

(c) Amphoteric oxide (d) Neutral oxide

Q.

An element forms an oxide which is acidic in nature.Is the element a metal or non-metal?

Q.

When silver metal reacts with sulfur in the air, a new substance is formed. This is called _________ and is formed through _________ change.

1. Tarnish & physical

2. Varnish & chemical

3. Tarnish & chemical

4. Varnish & physical

Q. The products formed when sodium reacts with cold water are:

1. sodium oxide
2. sodium hydroxide
3. hydrogen gas
4. water

Q.

The unwanted earthly materials present in an ore are called ___.

Q. When a piece of charcoal is heated, a certain gas is evolved.The evolved gas is tested by using moist red and blue litmus paper.The evolved gas is __(i)__, which is __(ii)__ in nature.

1. (i) - carbon dioxide, (ii) - acidic
2. (i) - carbon dioxide, (ii) - basic
3. (i) - sulphur dioxide, (ii) - acidic
4. (i) - sulphur dioxide, (ii) - basic

Q.

Rohan placed an iron nail in copper sulphate solution.

(a) What will he observe after one hour?

(b) What will be the colour change?

(c) Give reason for the change in colour observed.

(d) Write the chemical equation for the reaction.