Change in Colour

Q.

When copper turnings are added to silver nitrate solution, a blue coloured solution is formed after some time. It is because of copper

1. oxidises silver from the solution.

2. forms a blue coloured complex with $AgN{O}_3$.

3. is oxidised to $C{u}^{2+}$.

4. is reduced to $C{u}^{2+}$.

Q. When iron filings are added to copper sulphate solution, confirms the occurrence of a chemical change.

1. evolution of gas
2. formation of ppt
3. change in colour

Q.

When copper turnings are added to the silver nitrate solution, a blue coloured solution is formed after some time. It is because copper ____.

1. oxidises silver from the solution.

2. forms a blue coloured complex with $AgN{O}_3$.

3. is oxidised to $C{u}^{2+}$.

4. is reduced to $C{u}^{2+}$.

Q.

Name three metals that react with steam to form hydrogen gas.

Q. When iron nail is dipped in a blue coloured copper sulphate solution then:

1. the colour of the solution changes to red.
2. the colour of the solution changes to green.
3. the copper is deposited on the iron nail.
4. a chemical change occurs.

Q.

When copper powder is heated, it gets coated with

1. black copper oxide

2. yellow copper oxide

3. red copper oxide

4. none of these

Q.

A Brown and bright element "x" when heated in presence of air turns into black substance “y”. If Hydrogen gas is passed-over this heating material again "x" is obtained. "x" and "y are-

1. Cu & CuO

2. S & SO₂

3. C & CO₂

4. Na & NaH

Q.

Copper reacts with oxygen vigorously at room temperature.

1. True
2. False

Q.

Oxidation reactions have some harmful effects. Comment on the sentence.

Q.

Write the chemical equation for the reaction of hot Aluminium with steam.

Q.

Metals like magnesium, zink and iron on heating react with steam to form hydrogen gas and their respective

1. hydroxides

2. oxides

3. hydrides

4. none of these

Q.

Iron nails were dipped in a blue solution kept in a test tube. After half an hour, it was observed that the colour of the solution has changed to light green. The blue and light green solutions are

1. copper sulphate and iron sulphate respectively

2. iron sulphate and copper sulphate respectively

3. copper and iron respectively

4. iron and copper respectively

Q.

An element X forms an oxide ${\mathrm{X}}_2\mathrm{O}$ The aqueous solution of ${\mathrm{X}}_2\mathrm{O}$ turns red litmus to blue

1. What is the nature of the oxide ${\mathrm{X}}_2\mathrm{O}$?
2. Is X a metal or non-metal?
3. Name another element similar to X?

Q. When iron nail is dipped in a blue coloured copper sulphate solution then:

1. the colour of the solution changes to red.
2. the colour of the solution changes to green.
3. the copper is deposited on the iron nail.
4. a chemical change occurs.

Q.

Silver objects become black and lose their shine when rusted.

1. True
2. False

Q. When iron nail is dipped in a blue coloured copper sulphate solution, which of the following observations are not seen:

1. the colour of the solution changes to red.
2. the colour of the solution changes to green.
3. the copper is deposited on the iron nail.
4. a chemical change occurs.

Q. ____ change is involved in the given image:

1. Physical
2. Chemical
3. Natural
4. Reversible

Q. In the reaction
CuSo4 + Fe gives FeSo4 + Cu, what is the colour of the copper in the in product part of the reaction ?

Q.

State what you would observe when : Hydrogen is passed over heated copper (II) oxide.

Q. When iron filings are added to copper sulphate solution, a confirms the occurrence of a chemical change.

1. evolution of gas
2. evolution of heat
3. change in colour

Q. Isha was cutting some apples but in the middle of it Harry took her to play volleyball. After coming back she saw a brown coating over the apple slices. This formation of brown coating is which kind of change?

1. Physical change
2. Chemical change
3. Reversible change
4. Irreversible change

Q. When iron nail is dipped in a blue coloured copper sulphate solution then:

1. the colour of the solution changes to red.
2. the colour of the solution changes to green.
3. the copper is deposited on the iron nail.
4. a chemical change occurs.

Q. When iron nail is dipped in a blue coloured copper sulphate solution, which of the following observations are not seen:

1. the colour of the solution changes to red.
2. the colour of the solution changes to green.
3. the copper is deposited on the iron nail.
4. a chemical change occurs.

Q. The characteristic(s) observed during the reaction between iron sulphate and zinc is/are:

1. colour change
2. formation of a precipitate
3. absorption of heat
4. evolution of heat

Q. When iron filings are added to copper sulphate solution, a confirms the occurrence of a chemical change.

1. evolution of gas
2. evolution of heat
3. change in colour

Q.

The reddish-brown fume coming out when lead nitrate is heated is known as

1. Nitrogen

2. Nitrogen trioxide

3. Nitrogen dioxide

4. Nitrogen monoxide

Q. Rotting of a banana can be identified by:

1. change in temperature
2. change in weight
3. change in colour
4. change in state

Q.

To get her house whitewashed, an officer bought 10 kg of quicklime from the market and dissolved in 30 litres of water.
She noticed that the water started boiling even when it was not being heated.
Choose the corresponding product formed and the type of reaction involved.

1. Product formed:- Limewater
   Type of reaction:- Endothermic
2. Product formed:- Slaked lime
   Type of reaction:- Exothermic
3. Product formed:- Limestone
   Type of reaction:- Exothermic
4. Product formed:- Limestone
   Type of reaction:- Endothermic

Q. When iron filings are added to copper sulphate solution, a confirms the occurrence of a chemical change.

1. evolution of gas
2. evolution of heat
3. change in colour

Q.

Mention the oxidizing agent and the reducing agent $\mathrm{Mg}+2\mathrm{HCl}\to {\mathrm{MgCl}}_2+{\mathrm{H}}_2$and give a reason in support of your answer.