Chemical Reactions (Reactions)

Question 1

What do you observe when methane and oxygen is heated?

Answer 1

When methane and oxygen is heated it forms carbon dioxide,water vapour, and energy

CH⁴ + 2O² →CO² + 2H²O + Energy

Question 2

What do you observe when sodium hydroxide reacts with dilute hydrochloric acid?

Answer 2

When sodium hydroxide reacts with dilute hydrochloric acid, it forms sodium chloride and water

NaOH + HCL → NaCL + H²O

Question 3

What do you observe when zinc reacts with dilute sulphuric acid?

Answer 3

When zinc reacts with dilute sulphuric acid, hydrogen gas is evolved with an effervescence.

Zn + H²SO⁴ → ZnSO⁴ +H² ↑

Question 4

What do you observe when sodium sulphite is treated with dilute hydrochloric acid?

Answer 4

When sodium sulphite is treated with dilute hydrochloric acid, a gas with suffocation odour (like burning sulphur) sulphur dioxide is liberated

Na²SO⁴ + 2HCL → 2NaCL + H²O + SO² ↑

Question 5

What do you observe when a few pieces of iron are dropped into a blue coloured copper sulphate solution?

Answer 5

When a few pieces of iron are dropped into a blue coloured copper sulphate solution, the blue colour of the solution fades and eventually turns into light green.

Fe + CuSO⁴ (aq) → Fe SO⁴ + Cu

Question 6

What do you observe when blue coloured copper sulphate reacts with hydrogen sulphide gas?

Answer 6

When blue coloured copper sulphate reacts with hydrogen sulphide gas, a black coloured substance,copper sulphide is formed

CuSO⁴ + H²S → CuS + H²SO⁴

Question 7

What do you observe when lead nitrate is heated strongly?

Answer 7

Observation: Lead nitrate is a white crystalline solid. When it is heated strongly, it decomposes to form a light yellow solid (lead monoxide), reddish-brown gas (nitrogen dioxide), and a colorless gas (oxygen).

Chemical Reaction: 2 Pb(NO3)2 → 2 PbO + 4 NO2 + O2

Question 8

What do you observe when a solution of silver nitrate is added to a solution of sodium chloride?

Answer 8

A white insoluble substance, silver chloride is formed

AgNO3 + NaCL + AgCL↓ + NaNO3

Question 9

WHat do you observe when ferrous sulphate solution is added to sodium hydroxide solution?

Answer 9

A dirty green precipitate of ferrous hydroxide is formed.

FeSO₄ + 2 NaOH → Fe(OH)₂ ↓ + Na₂SO₄

Question 10

What do you observe when hydrogen sulphide and chlorine react together?

Answer 10

The reaction produces sulphur and hydrogen chloride.

H₂S + Cl₂ → 2 HCl + S (yellow precipitate)

Question 11

What do you observe when ammonia and hydrogen chloride gases react together?

Answer 11

They produces ammonium chloride which is a white solid.

NH₃ + HCl → NH₄Cl

Question 12

What do you observe when sodium comes in contact with cold water?

Answer 12

An explosive reaction occurs.
2 Na + 2 H₂O → 2 NaOH + H₂

Question 13

What do you observe when few drops of dilute sulphuric acid are added to an aqueous solution of barium chloride?

Answer 13

A white precipitate of barium sulphate is formed.
BaCl₂ + H₂SO₄ → BaSO₄ ↓ + 2 HCl

Question 14

What do you observe when iron and sulphur powder are heated?

Answer 14

They react to form new substance, iron sulphide.
Fe + S –> FeS

Question 15

Name a photochemical reaction.

Answer 15

Photosynthesis is a chemical reaction in which food is prepared by the leaves in the presence of light.

6 CO₂ + 6 H₂O + light energy → C₆H₁₂O₆ + 6 O₂

Question 16

Name an electrochemical reaction.

Answer 16

Water decomposes unto hydrogen and oxygen when electric current is passed.

2 H₂O →[electric current] 2 H₂ + O₂

Question 17

What do you observe when nitrogen and hydrogen are at a high pressure?

Answer 17

It produces ammonia gas.
N₂ + 3 H₂ →[high pressure, catalyst] 2 NH₃

Question 18

Give two examples of positive catalyst.

Answer 18

1. Manganese dioxide in 2 KClO₃ →[MnO₂] 2 KCl + 3O₂
2. Iron in N₂ + 3 H₂ →[Fe] 2 NH₃

Question 19

Name a negative catalyst or inhibitor.

Answer 19

1. Phosphoric acid to decrease the rate of
   decomposition of hydrogen peroxide.
2. Alcohol

Question 20

What do you observe when carbon burns in oxygen?

Answer 20

It forms a gaseous compound, carbon dioxide.

C + O₂ →[heat] CO₂

Question 21

What do you observe when carbon monoxide burns in the presence of oxygen?

Answer 21

It forms a single product carbon dioxide.
2 CO + O₂ → 2 CO₂

Question 22

Question:
What will be the product when Hydrogen and Chlorine react together in diffuse sunlight?

Reactants:
Reactant 1: Hydrogen (H₂)
Reactant 2: Chlorine (Cl₂)

Answer 22

Answer:
When hydrogen and chlorine react in diffuse sunlight, they form hydrogen chloride (HCl) gas.

Complete the equation:
H₂ + Cl₂ →[sunlight] 2 HCl

Question 23

Question:
What will be the product when Phosphorus trichloride and Chlorine react together under heat?

Reactants:
Reactant 1: Phosphorus trichloride (PCl₃)
Reactant 2: Chlorine (Cl₂)

Answer 23

Answer:
When phosphorus trichloride reacts with chlorine under heat, phosphorus pentachloride (PCl₅) is formed.

Complete the equation:
PCl₃ + Cl₂ →[heat] PCl₅

Question 24

Question:
What will be the product when Sulfur dioxide and Water react together?

Reactants:
Reactant 1: Sulfur dioxide (SO₂)
Reactant 2: Water (H₂O)

Answer 24

Answer:
When sulfur dioxide reacts with water, it forms sulfurous acid (H₂SO₃).

Complete the equation:
SO₂ + H₂O → H₂SO₃

Question 25

Question:
What will be the product when Nitrogen pentoxide and Water react together?

Reactants:
Reactant 1: Nitrogen pentoxide (N₂O₅)
Reactant 2: Water (H₂O)

Answer 25

Answer:
When nitrogen pentoxide reacts with water, it forms nitric acid (HNO₃).

Complete the equation:
N₂O₅ + H₂O → 2 HNO₃

Question 26

Question:
What will be the product when Calcium oxide (quicklime) and Water react together?

Reactants:
Reactant 1: Calcium oxide (CaO)
Reactant 2: Water (H₂O)

Answer 26

Answer:
When calcium oxide (quicklime) reacts with water, it forms calcium hydroxide (slaked lime).

Complete the equation:
CaO + H₂O → Ca(OH)₂

Question 27

what do you observe when mercuric oxide is heated

Answer 27

It decomposes to form two elements, mercury and oxygen.
2HgO →[heat] 2Hg + O₂

Question 28

What do you observe when potassium nitrate is heated?

Answer 28

It decomposes to produce a compound, potassium nitrate and element oxygen

2 KNO₃ →[heat] 2 KNO₂ + O₂

Question 29

What do you observe when calcium carbonate is strongly heated?

Answer 29

It decomposes to form two compounds, calcium oxide and carbon dioxide.

CaCO₃ →[heat] CaO + CO₂

Question 30

Question:
What will be the product when Potassium chlorate is heated?

Reactants:
Reactant 1: Potassium chlorate (KClO₃)

Answer 30

Answer:
When potassium chlorate is heated, it decomposes to form potassium chloride and oxygen.

Complete the equation:
2 KClO₃ →[heat] 2 KCl + 3 O₂

Question 31

Question:
What will be the product when Copper hydroxide is heated?

Reactants:
Reactant 1: Copper hydroxide (Cu(OH)₂)

Answer 31

Answer:
When copper hydroxide is heated, it decomposes to form copper(II) oxide and water.

Complete the equation:
Cu(OH)₂ →[heat] CuO + H₂O

Question 32

Question:
What will be the product when Copper carbonate is heated?

Reactants:
Reactant 1: Copper carbonate (CuCO₃)

Answer 32

Answer:
When copper carbonate is heated, it decomposes to form copper(II) oxide and carbon dioxide.

Complete the equation:
CuCO₃ →[heat] CuO + CO₂

Question 33

Question:
What will be the product when Hydrogen peroxide is heated?

Reactants:
Reactant 1: Hydrogen peroxide (H₂O₂)

Answer 33

Answer:
When hydrogen peroxide is heated, it decomposes to form water and oxygen.

Complete the equation:
2 H₂O₂ →[heat] 2 H₂O + O₂

Question 34

Question:
What will be the product when Zinc and Diluted Hydrochloric Acid react together?

Reactants:
Reactant 1: Zinc (Zn)
Reactant 2: Diluted hydrochloric acid (HCl)

Answer 34

Answer:
When zinc reacts with diluted hydrochloric acid, it produces zinc chloride and hydrogen gas.

Complete the equation:
Zn + 2 HCl → ZnCl₂ + H₂

Question 35

Question:
What will be the product when Zinc and Diluted Sulfuric Acid react together?

Reactants:
Reactant 1: Zinc (Zn)
Reactant 2: Diluted sulfuric acid (H₂SO₄)

Answer 35

Answer:
When zinc reacts with diluted sulfuric acid, it produces zinc sulfate and hydrogen gas.

Complete the equation:
Zn + H₂SO₄ → ZnSO₄ + H₂

Question 36

Question:
What will be the product when Sodium reacts with Hydrogen in cold water?

Reactants:
Reactant 1: Sodium (Na)
Reactant 2: Hydrogen (H₂)
Reactant 3: Cold water (H₂O)

Answer 36

Answer:
When sodium reacts with hydrogen and cold water, it forms sodium hydroxide and hydrogen gas.

Complete the equation:
2 Na + 2 H₂O → 2 NaOH + H₂

Question 37

Question:
What will be the product when Potassium reacts with Hydrogen in cold water?

Reactants:
Reactant 1: Potassium (K)
Reactant 2: Hydrogen (H₂)
Reactant 3: Cold water (H₂O)

Answer 37

Answer:
When potassium reacts with hydrogen and cold water, it forms potassium hydroxide and hydrogen gas.

Complete the equation:
2 K + 2 H₂O → 2 KOH + H₂

Question 38

Question:
What will be the product when Potassium bromide reacts with Chlorine?

Reactants:
Reactant 1: Potassium bromide (KBr)
Reactant 2: Chlorine (Cl₂)

Answer 38

Answer:
When potassium bromide reacts with chlorine, it forms potassium chloride and bromine gas.

Complete the equation:
2 KBr + Cl₂ → 2 KCl + Br₂

Question 39

Question:
What will be the product when Potassium iodide reacts with Chlorine?

Reactants:
Reactant 1: Potassium iodide (KI)
Reactant 2: Chlorine (Cl₂)

Answer 39

Answer:
When potassium iodide reacts with chlorine, it forms potassium chloride and iodine gas.

Complete the equation:
2 KI + Cl₂ → 2 KCl + I₂

Question 40

Question:
What will be the product when Potassium iodide reacts with Chlorine?

Reactants:
Reactant 1: Potassium iodide (KI)
Reactant 2: Chlorine (Cl₂)

Answer 40

Answer:
When potassium iodide reacts with chlorine, it forms potassium chloride and iodine gas.

Complete the equation:
2 KI + Cl₂ → 2 KCl + I₂

Question 41

Question:
What will be the product when Barium chloride reacts with Sodium sulfate?

Reactants:
Reactant 1: Barium chloride (BaCl₂)
Reactant 2: Sodium sulfate (Na₂SO₄)

Answer 41

Answer:
When barium chloride reacts with sodium sulfate, barium sulfate (BaSO₄) forms as a white precipitate, and sodium chloride is produced.

Complete the equation:
BaCl₂ + Na₂SO₄ → BaSO₄ (↓) + 2 NaCl

Question 42

Question:
What will be the product when Silver nitrate reacts with Hydrochloric acid?

Reactants:
Reactant 1: Silver nitrate (AgNO₃)
Reactant 2: Hydrochloric acid (HCl)

Answer 42

Answer:
When silver nitrate reacts with hydrochloric acid, it forms silver chloride as a white precipitate and nitric acid.

Complete the equation:
AgNO₃ + HCl → AgCl (↓) + HNO₃

Question 43

Question:
What will be the product when Copper sulfate reacts with Sodium hydroxide?

Reactants:
Reactant 1: Copper sulfate (CuSO₄)
Reactant 2: Sodium hydroxide (NaOH)

Answer 43

Answer:
When copper sulfate reacts with sodium hydroxide, it forms copper hydroxide as a blue precipitate and sodium sulfate.

Complete the equation:
CuSO₄ + 2 NaOH → Cu(OH)₂ (↓) + Na₂SO₄

Question 44

Question:
What will be the product when Lead nitride reacts with Ammonium hydroxide?

Reactants:
Reactant 1: Lead nitride (Pb₃N₂)
Reactant 2: Ammonium hydroxide (NH₄OH)

Answer 44

Answer:
When lead nitride reacts with ammonium hydroxide, it forms lead hydroxide and ammonia gas.

Complete the equation:
Pb₃N₂ + 6 NH₄OH → 3 Pb(OH)₂ + 2 NH₃

Question 45

Question:
What will be the product when Calcium chloride reacts with Sodium hydroxide?

Reactants:
Reactant 1: Calcium chloride (CaCl₂)
Reactant 2: Sodium hydroxide (NaOH)

Answer 45

Answer:
When calcium chloride reacts with sodium hydroxide, it forms calcium hydroxide as a precipitate and sodium chloride.

Complete the equation:
CaCl₂ + 2 NaOH → Ca(OH)₂ (↓) + 2 NaCl

Question 46

Question:
What will be the product when Sodium hydroxide reacts with Hydrochloric acid?

Reactants:
Reactant 1: Sodium hydroxide (NaOH)
Reactant 2: Hydrochloric acid (HCl)

Answer 46

Answer:
When sodium hydroxide reacts with hydrochloric acid, it forms sodium chloride and water.

Complete the equation:
NaOH + HCl → NaCl + H₂O

Question 47

Question:
What will be the product when Zinc oxide reacts with Nitric acid?

Reactants:
Reactant 1: Zinc oxide (ZnO)
Reactant 2: Nitric acid (HNO₃)

Answer 47

Answer:
When zinc oxide reacts with nitric acid, it forms zinc nitrate and water.

Complete the equation:
ZnO + 2 HNO₃ → Zn(NO₃)₂ + H₂O

Question 48

Question:
What will be the product when Potassium hydroxide reacts with Sulfuric acid?

Reactants:
Reactant 1: Potassium hydroxide (KOH)
Reactant 2: Sulfuric acid (H₂SO₄)

Answer 48

Answer:
When potassium hydroxide reacts with sulfuric acid, it forms potassium sulfate and water.

Complete the equation:
2 KOH + H₂SO₄ → K₂SO₄ + 2 H₂O

Question 49

Question:
What will be the product when Copper oxide reacts with Nitric acid?

Reactants:
Reactant 1: Copper oxide (CuO)
Reactant 2: Nitric acid (HNO₃)

Answer 49

Answer:
When copper oxide reacts with nitric acid, it forms copper nitrate and water.

Complete the equation:
CuO + 2 HNO₃ → Cu(NO₃)₂ + H₂O