Class 10 Science Chapter 2 MCQ

Here, all the statements are correct. Hence, your answer will be option [D].

HCl is a strong acid. When HCl is mixed with water, its molecules dissociate completely to furnish H+ ions and Cl– ions. This H+ ion combines with water molecules to produce hydronium ions.

Acids turn blue litmus solution to red. They have a sour taste as in case of vinegar and are sticky to touch. On the other side, bases turn red litmus solution to blue. They are bitter in taste as in case of baking soda and are slippery to touch.

If a solution turns universal indicator green, then it will be a neutral solution (which is neither acidic nor basic). Thus, water will produce a green colour with universal indicator.

Firstly, Bleaching powder (CaOCl2) is used bleach clothes and removes colour from clothes. It decomposes on reaction with water and releases chlorine which acts as oxidising, bleaching and disinfecting agent. Baking soda is a natural antacid. It is used to relieve acidity in stomach and heart burn. Washing soda is used in the preparation of glass, soap and paper industries. Sodium chloride is used to produce H2 and Cl2 gases. And lastly, Aqueous sodium chloride on electrolysis yields hydrogen and chlorine.

C2H5OH is not a base. C2H5OH or ethyl alcohol has a functional OH– group. It cannot dissociate ions in a solution. Thus it cannot be a basic compound.

Sodium oxide (Na2O) is a metal oxide, so it is a base; and sodium hydroxide (NaOH) is a metal hydroxide, so it is also a base.

Aqua-regia is used for the dissolution of gold. It is a solution of concentrated HNO3 and concentrated HCl in the ratio of 1:3. Thus this solution is strongly acidic and is used to dissolve gold.

Here, all the statements are correct. Hence, your answer will be option [D].

Lime juice is acidic in nature. It has high amount of citric acid present in it.

All the acid solutions conduct electricity. Here, all the statements are correct except one. Hence, your answer will be option [D].

Generally, acids are stored in containers made of glass and ceramics because they are not attacked by acids. Acids are never stored in metal containers because they gradually corrode and eat up the metal container.

When the pH of an aqueous solution is higher, acidic properties are weak. Thus it is a base. When the pH an aqueous solution is lower, basic properties are weak. Thus it is an acid. Note: In 1909 Sorenson devised a scale (known as pH scale) on which the strength of acid solutions as well as basic solutions could be represented by making use of the hydrogen ion concentrations in them. A pH scale is used to measure the acidic and basic strength of an aqueous solution. This scale is marked from 0 to 14. A solution is neutral if its pH value is 7. An acidic solution has a pH less than 7. This means an acidic solution has more concentration of H+ ions. A basic solution has a pH more than 7. This means a basic solution has more concentration of OH– ions.

Here, all the statements are correct. Hence, your answer will be option [D].

Here, all the statements are correct. Hence, your answer will be option [D].

Water is added to concentrated acid to dilute it, then a large amount of heat is evolved at once. This heat changes some of the water to steam explosively which can splash the acid on our face or clothes and cause acid burns. Note: When a concentrated acid is added to water for preparing a dilute acid, then the heat is evolved gradually, and easily absorbed by the large amount of water

When sodium hydrogen carbonate is added to acetic acid, carbon dioxide (CO2) gas is evolved. Sodium hydrogen carbonate + Acetic acid → Sodium acetate + water + carbon dioxide You can easily understand by this equation: NaHCO3 + CH3COOH → CH3COONa + H2O + CO2

The acids prepared from the minerals of the earth are called mineral acids. Mineral acids are manmade acids. The three most common mineral acids are: Hydrochloric acid, Sulphuric acid and Nitric acid. Concentrated mineral acids are very dangerous. They can burn our hands and clothes. These acids should be handled with care.

Firstly, we have to understand that a strong base cannot be used to neutralise the acid as it can corrode the skin. Wash the hand immediately with plenty of water as it helps to wash away most of the acid. Thereafter apply a paste of baking soda (NaHCO3) to neutralise the little acid if any, left over the hand. Baking soda has weak basic properties that is used to neutralise the acid.

The increasing order of acid strength is water < acetic acid < hydrochloride acid. Hydrochloride acid is a mineral acid and ionises completely in water. That’s why it is a strong acid. Acetic acid is an organic acid and ionises only partially in water. That’s why it is a weak acid. Water is almost neutral in nature. In pure water number of positive hydrogen ions is equal to the negative ions.

Here, all the statements are correct. Hence, your answer will be option [D].

The most common indicator used for testing acids and bases in the laboratory is litmus. Litmus can be used in the form of litmus solution or in the form of litmus paper. It is of two types blue litmus and red litmus.

Calcium phosphate Ca3(PO4)2 is basic salt, as it is formed by the combination of a weak acid (phosphoric acid) and slightly stronger base (calcium hydroxide). Bacteria feed on sugars commonly found in foods and produce acids in the mouth decreasing the pH level to 5.5 or lower. Thus, eroding the enamel that is basic in nature.

The aqueous solution is a base as it turns red litmus solution blue. An acidic solution such as hydrochloric acid (HCl) would reverse the change. In contrast, hydrochloric acid would turn blue litmus solution to red.

Baking soda does not contain water of crystallization. The chemical formula of baking soda is NaHCO3. Its formula does not show any association with water molecules. Other three contain water of crystallization blue vitriol (CuSO4.5H2O), washing soda (Na2CO3.10H2O) and gypsum (CaSO4.2H2O).