Science 2 Marks Questions

Factory wastes contain acids. Therefore, these wastes, when thrown directly to water bodies, harm aquatic lives. Hence, these wastes are neutralised with basic chemicals before disposing to water bodies.

When an ant bites, it injects formic acid into the skin. Calamine solution contains zinc carbonate which is basic in nature. Therefore, it is applied on the skin to neutralize the effect of formic acid.

This is because during acidity, an excess of acids is produced in the stomach. An antacid contains base, such as milk of magnesia. These bases react with excess of acids and neutralize their effect, thus giving us relief.

Sometimes when we consume spicy food, our stomach releases excess of hydrochloric acid which causes indigestion or acidity. An antacid tablets contains base like milk of magnesia (magnesium hydroxide), it neutralises the effect of excessive acid and bring reliefs.

On the basis of the property of acids and bases he can differentiate all the drinks. Like an Acidic drink will have a sour taste and will turn blue litmus red. A basic drink will turn red litmus red. A neutral drink will not change the colour of red or blue litmus. A part from this he can also use turmeric solution for checking the drinks.

We can find out by using an indicator like litmus paper. If on putting some drops of the liquid on red litmus paper it turns blue, the liquid is a base and if it remains unchanged then it is an acid.

1. Litmus (blue litmus paper).
2. Turmeric.

No change will be observed, because baking soda in solid state do not contain free ions to more while if we use baking soda solution due to presence of free ions, now it could litmus paper will convert into blue, because baking soda solution is basic in nature.

Salts are the ionic compounds generally formed by neutralisation of an acid with base. They can be acidic, basic as well as neutral. Example acidic salts: sodium bicarbonate, basic salts: magnesium chloride, neutral salt: sodium chloride.

Neutralization is a process in which an acid solution when mixed with base solution, react with each other to produce a salt and water along with generation of heat. Salt so produced, may be acidic, basic or neutral in nature. In this process the acidic nature of the acid and the basic nature of the base are destroyed. Acid + base salt + water. (heat is evolved)

The wastes of many factories contain acids. If they are allowed to flow into the water bodies, the acids will kill fish and other organisms. The factory wastes are, therefore, neutralised by adding basic substances into it.

Indicators are special type of substance that are used to taste whether a substance is acidic or basic in nature. It change the colour of acidic or basis substances when added into it. Turmeric, litmus, etc. are some natural indicators.

China rose petals when added to warm water, form a light pink coloured solution which may be used as an indicator. This indicator turns acidic solution to magenta (deep pink) and basic solution to green.

When an ant bites, it injects formic acid into the skin. Calamine solution contains zinc carbonate which is basic in nature. Therefore, it is applied on the skin to neutralize the effect of formic acid.

Acid can be tested in any substance by the following methods:

• Take a drop of the dilute solution of the substance on the tips of your tongue. If tastes sour, it is acidic.
• Dip a blue litmus paper in the solution. If the colour of the litmus paper turns red, the solution is acidic.

If the wastes of a factory flow into water bodies, it can cause a threat to the lives of aquatic creatures and to anybody who drink the water. Since, the acids present in the factory waste will kill the fish and other aquatic organisms.

In neutralisation reaction, heat is always produced or evolved. The evolved heat raises the temperature of the reaction mixture. Therefore, if we touch the test tube immediately after the neutralisation reaction, it is found to be hot.
Acid + Base → Salt + Water (heat is evolved)

Litmus is extracted from lichens. It is most commonly used as an indicator to determine the chemical nature of substance. It has mauve or purple colour in distilled water. When it is added to an acidic solution, it turns red and when added to a basic solution, it turns blue. It is available in the form of a solution, or in the form of strips of paper, known as litmus paper. Generally, it is available as red and blue litmus paper.

This is because during acidity, an excess of acids is produced in the stomach. An antacid contains base, such as milk of magnesia. These bases react with excess of acids and neutralize their effect, thus giving us relief.

Factory wastes contain acids. Therefore, these wastes, when thrown directly to water bodies, harm aquatic lives. Hence, these wastes are neutralised with basic chemicals before disposing to water bodies.

No, because orange juice is acidic in nature. Instead she should be given an antacid (milk of magnesia), which is base and neutralise the acidity. Milk of magnesia contains a base magnesium hydroxide which reacts with the acid and cures indigestion.

Wasp sting inject a liquid in the skin which is acidic in nature. Hence, baking soda is the appropriate remedy as it is basic in nature and neutralises the acid.

The sting of an ant contains formic acid. When an ant bites, it injects the acidic liquid into the skin. The effect of the sting can be neutralised by rubbing some moist solution of a basic substance such as baking soda (sodium hydrogen carbonate) or calamine solution, which contains zinc carbonate.

Salts are the ionic compounds generally formed by neutralisation of an acid with base. They can be acidic, basic as well as neutral. Example acidic salts: sodium bicarbonate, basic salts: magnesium chloride, neutral salt: sodium chloride.

We can get solid sodium chloride by evaporation method. Water changes to vapour form during evaporation and solid sodium chloride is left in the container.