Samacheer Class 9 Science - Acids, Bases and Salts

Options:

• (H_2)
• (O_2)
• (CO_2)

Answer:

• citric acid
• ascorbic acid

Answer:
Ascorbic acid

Orange also contains citric acid, but vitamin C is ascorbic acid.

• Inorganic acids
• Weak acids

Answer:
Inorganic acids

• green
• red
• orange

Answer:
Red

• (NO_2)
• (SO_2)
• (CO_2)

Answer:

• red
• white
• blue

Answer:
Blue

Organic Acids

Acids present in plants and animals.

Examples:

• Citric acid
• Acetic acid
• Lactic acid

Inorganic Acids

Acids obtained from rocks and minerals.

Examples:

• Hydrochloric acid
• Sulphuric acid
• Nitric acid

Sulphuric Acid ((H_2SO_4))

• Called King of Chemicals
• Used in batteries
• Used in manufacture of chemicals

Hydrochloric Acid ((HCl))

• Used as cleaning agent

Citric Acid

• Food preservative
• Effervescent salts

Nitric Acid ((HNO_3))

• Fertilizers
• Dyes
• Paints
• Explosives

Oxalic Acid

• Removes stains
• Bleaching agent

Carbonic Acid

• Used in aerated drinks

Tartaric Acid

• Used in baking powder

Answer:

Different crops require different soil pH.

Soil pH affects nutrient availability and crop growth.

Aqua Regia

Mixture of:

Uses

• Dissolves gold and platinum
• Cleaning and refining gold

Uses

• Plastering fractured bones
• Making statues and casts

Acid A

Gives one hydrogen ion per molecule.

Answer:

(Hydrochloric acid)

Acid B

Gives two hydrogen ions per molecule.

Answer:

(Sulphuric acid)

King of Chemicals

Sulphuric acid

Answer:

Aqua regia is freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in ratio:

(a)

Incorrect:

“Washing soda is used for making cakes soft.”

Correct:

Baking soda ((NaHCO_3)) is used for making cakes and bread soft and spongy.

(b)

Incorrect:

“Calcium sulphate hemihydrate is used in bleaching.”

Correct:

Bleaching powder ((CaOCl_2)) is used in textile bleaching.

Answer:

Reaction between acid and base producing salt and water is called neutralization.

Correction made:
NaCl is not best example of anhydrous salt in this context.

Correction made:
Original answer incorrectly mentioned “pink” for acid in methyl orange test.

Sodium Hydroxide ((NaOH))

• Soap manufacture

Calcium Hydroxide ((Ca(OH)_2))

• White washing

Magnesium Hydroxide ((Mg(OH)_2))

• Antacid medicine

Ammonium Hydroxide ((NH_4OH))

• Removes grease stains

# Common Salt ((NaCl))

• Food seasoning
• Preservative

# Washing Soda ((Na_2CO_3))

• Softens hard water
• Glass and soap industry

# Baking Soda ((NaHCO_3))

• Baking powder
• Fire extinguishers
• Antacid

# Bleaching Powder ((CaOCl_2))

• Disinfectant
• Bleaching agent

# Plaster of Paris ((CaSO_4 \cdot \frac{1}{2}H_2O))

• Bone plaster
• Statues

Answer:

Sulphuric acid is widely used in manufacture of numerous chemicals and industrial products.

Hence it is called:

King of Chemicals