Science [1 Mark Questions]

A base is any substance that neutralizes acid. It may or may not be soluble in water. Those bases which are soluble in water are called alkalis. They are soapy to touch, bitter and corrosive. Thus an alkali is a kind of base.
For example: NaOH, KOH etc.

It makes the survival of aquatic life difficult because when the substances of acid rain mixes with the water the water gains the substances and it becomes acidic and so no life is possible in acidic water so it is difficult for the aquatic life to survive in acidic water.

The pH decreases as milk changes into curd. This is because of the formation of lactic acid which as the name suggests is acidic in nature, curd is of the range 4.5 - 5.5

The gas liberated when hydrochloric acid reacts with a metal is hydrogen gas. If the gas released is indeed hydrogen, then the splinter will extinguish with a pop sound.

1. pH = 9: Alkaline.
2. pH = 4: Acidic.
3. pH = 7: Neutral.
4. pH = 1: Acidic.
5. pH = 10: Alkaline.
6. pH = 3: Acidic.

Blue.

Hydrochloric acid.

pH of pure water = 7

Plaster of Paris.

Base.

Alkaline reaction: Solution Y (pH = 8)
Acidic reaction: Solution X (pH = 4)

Litmus.

Gypsum.

1. Yellow.
2. Blue.
3. Green.

If the soil is acidic and improper for cultivation, then to increase the basicity of soil, the farmer would treat the soil with quick lime or slaked lime or chalk.

PH 1 is more acidic higher the hydronium ion concentration lower it's ph value. Acidic and basic are two extremes that describe a chemical property chemicals. Mixing acids and bases can cancel out or neutralize their extreme effects. A substance that is neither acidic nor basic is neutral. The pH scale measures how acidic or basic a substance is. The pH scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic.

Chlorine is used for treating water. It is a product formed during the chlor alkali process.

Solution of pH = 2 is more acidic.

Washing soda has detergent properties because it can remove dirt and grease from dirty clothes.

When the pH in the mouth falls to around 5.5, tooth decay begins. As the acidity in the mouth increases, the acid reacts with the tooth enamel and causes tooth decay.

Sodium chloride.

Chlorine.

Rock salt. It is mined from the underground deposits just like coal.

Acid in tomato: Citric acid and oxalic acid, with chemical composition of HOOCCOOH.

When the soil is too acidic, it is treated with bases like quicklime or slaked lime or chalk.

Solution A (pH = 3.0) will turn litmus from solution blue to red Solution B (pH = 9.5) will turn phenolphthalein from colourless to pink.

pH < 7 is acidic
pH > 7 is basic
pH = 7 is neutral
Since the pH is 6.5, i.e., below 7, so the soup is acidic in nature and is sour to taste.

It sets into a hard mass in about 30 mins.

Alkali salts are soluble hydroxides of alkali metals and alkaline earth metals, of which common examples are, Sodium hydroxide–often called "caustic soda" Potassium hydroxide–commonly called "caustic potash" Lye–generic term for either of the previous two or even for a mixture.

​​​​Baking powder though composed of an alkali called sodium bicarbonate yet there is the presence of tartaric acid in it.
If this acid would not be present in the powder, then the taste of the food materials like cake, cookies and bread might taste bitter due to excess amount of sodium bicarbonate.

The blue copper sulphate crystals contain water of crystallization as it is blue in colour.

Carbon and Sulphur being non-metals form acidic oxides.

They all produce hydroxide ions when dissolved in water.

This is because the presence of moisture can cause the slow setting of plaster of Paris by bringing about its hydration.

1. Red.
2. Red.

Plaster of Paris.

Bleaching powder.