EASY
Earn 100

The decomposition of silver chloride occurs by which of the following ?

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Important Questions on Matter and Its States

HARD

 Write the products of following chemical reaction:

2FeSO4.7H2OMX+Y+Z

HARD

Consider the following statements:

1. Reactions in which heat is released along with the formation of products are called exothermic chemical reactions.
2. Reactions in which energy is absorbed, are known as endothermic reactions.

Which of the statements given above is/are correct?

MEDIUM
The inner surface of food cans are coated with tin and not with zinc because _____.
EASY
Which of the following mixtures of gases are used for welding of metals?
MEDIUM

Consider the following reactions:

Zn(s) + CuSO4(aq)
Fe(s)+ ZnSO4(aq)
Zn(s)+ FeSO4(aq)

Which of the above chemical reaction(s) will take place?

MEDIUM
Anita prepared a fresh solution of sodium hydroxide in a test tube. She dropped a small piece of aluminium foil into it and then brought a burning matchstick near the mouth of the test tube. She hears a pop sound. The pop sound indicates the presence of _____.
HARD
Which of the following is not a chemical reaction?
EASY
Iron nails are dipped into blue copper sulphate solution. After sometime, iron nails are:
EASY

Consider the following reaction:

CuO + H2Heat Cu + H2O   

Which species get oxidized in the given chemical reaction?

MEDIUM

Sodium and potassium are stored in kerosene. Give reason. The following reasons are given by class VIII students.

1. Both are highly reactive and react with carbon dioxide in the atmosphere.

2. Both are highly toxic and give off toxic fumes.

3. Both are highly reactive and react with oxygen in the atmosphere.

4. Kerosene helps cut off the reaction of the metals with oxygen in the air.

Select the most appropriate reason(s) given by class VIII students.

MEDIUM
Rekha's mother has tarnished copper vessels. Her neighbour advised her to use lemon or tamarind juice for cleaning. Which of the following properties of sour substances is effective in cleaning the vessels?
MEDIUM

Student (X) has taken five 100 mL beakers and labelled them A, B, C, D and E and also added 50 mL of water in each beaker. After that, she added the following composition of substance in each beaker. It is as follows:

Beaker A: Copper sulphate CuSO4+ Zinc granule (Zn)
Beaker B: Copper sulphate CuSO4+ Iron nail (Fe)
Beaker C: Zinc sulphate ZnS04+ Copper turnings (Cu)
Beaker D: Iron sulphate FeS04+ Copper turnings (Cu)
Beaker E: Zinc sulphate ZnS04+ Iron nail (Fe).

Which of the following concepts is used to study the given reactions?

EASY
 When a copper plate is exposed to moist air for long, then it acquires a dull green coating. The green material is _____.
HARD
When we add aluminium foil to freshly prepared sodium hydroxide solution, a gas is produced. Which of the following correctly states the property of this gas?
HARD

Select from the following the reactions that is/are possible.

1. Al2(SO4)3(aq)+Cu(s)  

2. FeSO4(aq)+Zn(s)

3. CuSO4(aq)+Fe(s)

4. Al2(SO4)3(aq)+Zn(s)

EASY
In which step of the water cycle does liquid water transform into gas?
EASY
In the above-demonstrated activity, which substance is formed when sulphur dioxide is dissolved in water?
MEDIUM
When copper turnings are heated with conc. undefined, it evolves _____ gas.
EASY
If acid burn occurs in the laboratory, then wash with plenty of water and before putting vaseline which of the following first-aids should he perform?