Chemistry · NDA previous year questions

A student heated some sulphur in a spatula and collected the gas 'X'. Which one among the following is correct about 'X'?

1. A.X is $\mathrm{S}{\mathrm{O}}_2$ and it turns moist litmus to blue
2. B.X is $\mathrm{S}{\mathrm{O}}_3$ and it turns moist litmus to red
3. C.X is $\mathrm{S}{\mathrm{O}}_2$ and it turns moist litmus to red
4. D.X is $\mathrm{S}{\mathrm{O}}_3$ and it turns dry litmus to blue

Human stomach produces acid 'X' which helps in digestion of food. Acid 'X' is :

1. A.acetic acid.
2. B.methanoic acid.
3. C.hydrochloric acid.
4. D.citric acid.

A bee-sting leaves an acid which causes pain and irritation. The injected acid is :

1. A.acetic acid.
2. B.sulphuric acid.
3. C.citric acid.
4. D.methanoic acid.

Silver ware turns black after a period of time due to formation of :

1. A.nitrate coating on silver.
2. B.sulphide coating on silver.
3. C.chloride coating on silver.
4. D.oxide coating on silver.

Which of the statements given below is/ are correct? Permanent hardness of water is due to the presence of soluble : 1. chloride of calcium. 2. bicarbonate of calcium. 3. sulphate of magnesium. 4. bicarbonate of magnesium. Select the correct answer using the code given below :

1. A.1 only
2. B.1 and 3 only
3. C.2 and 4
4. D.1, 2 and 3

Which one among the following methods is not effective in removing arsenic from contaminated ground water?

1. A.Boiling
2. B.Reverse osmosis
3. C.Ion exchange
4. D.Coagulation-adsorption

Bronze is often used to make statues and medals whereas brass is used in making utensils, scientific apparatus and cartridges. Both brass and bronze are copper containing alloys, yet they differ in their chemical composition for additionally containing:

1. A.Zinc in brass and tin in bronze.
2. B.Chromium in brass and nickel in bronze.
3. C.Nickel in brass and tin in bronze.
4. D.Iron in brass and nickel in bronze.

Which one among the following statements about stomach is not correct?

1. A.Stomach acts as a temporary reservoir
2. B.Stomach mixes food with gastric juice
3. C.Stomach secretes lipase and amylase in gastric juice
4. D.Rate of stomach emptying depends on the type of food

By which one among the following mechanism, soap removes dirt (soil) from cloth ?

1. A.Soap dissolves the soil as such
2. B.Soap reacts with soil and converts them into soluble silicates
3. C.Soap takes away the oily part of the soil and thus separates the soil from the cloth
4. D.The soap molecules bind with the soil, lift the soil and keep it suspended which can then be rinsed away

Which one among the following statements is not correct about graphite ?

1. A.It is the most stable allotrope of carbon
2. B.It is an electrically conducting material
3. C.Crystalline spherical beads of graphite have very good lubricating property under dry conditions
4. D.It is the highest grade of coal

Which one among the following is not a property of salt ?

1. A.Salts have ordered packing arrangements called lattices
2. B.Salts have low melting points but high boiling points
3. C.Salts are brittle
4. D.Salts conduct electricity when dissolved in water or even in the molten state

Which among the following statements with regard to pH scale is/are correct ? 1. It is a logarithmic scale 2. The scale is limited to 0—14 because the ionic product of water is about $10^{-14}$ 3. The lower the value of pH the greater is the acidity of the solution Select the correct answer using the code given below :

1. A.1 and 2 only
2. B.1, 2 and 3
3. C.1 and 3 only
4. D.2 only

An oxidizing agent is a substance which :

1. A.increases the oxidation number of an element in a given substance
2. B.decreases the oxidation number of an element in a given substance
3. C.is oxidized itself in an oxidation-reduction reaction
4. D.loses electrons in an oxidation-reduction reaction

Neutral water with pH about 7 becomes slightly acidic when aerated. This is because :

1. A.oxygen from air is dissolved in the water which makes the water acidic
2. B.dirt, which get contaminated with the water during aeration makes the water acidic
3. C.ultraviolet radiation dissociates water molecules and makes water acidic
4. D.carbon-dioxide from air is dissolved

Which one of the following statements is not correct ?

1. A.Diesel burns with air in a diesel engine at a high temperature at which nitrogen and oxygen from air can combine whereas petrol burns at a lower temperature at which nitrogen and oxygen can not combine
2. B.Diesel contains some nitrogenous compounds whereas petrol does not
3. C.Nitrogen from air is easily dissolved in diesel but it is not soluble in petrol
4. D.A catalyst is used in diesel engines which contains nitrogen whereas petrol engines do not need such catalysts

Consider the following statements with regard to the properties of water : 1. Water is a good solvent for ionic compound but poor solvent for covalent compound 2. Water is a good solvent for covalent compound but poor solvent for ionic compound 3. Water has maximum density at the temperature 277 K Which of the statements given above are correct ?

1. A.1 and 3 only
2. B.2 and 3 only
3. C.1 and 2 only
4. D.1, 2 and 3

Calcium carbonate is naturally available as limestone and can also be synthesized from quick lime. It is seen that the composition of the elements in both the natural and synthetic calcium carbonate are same. The validity of which one among the following laws is confirmed by this observation ?

1. A.Law of conservation of mass
2. B.Law of definite proportion
3. C.Law of multiple proportion
4. D.Avogadro’s law

When aqueous solutions of two salts are mixed, the third salt formed may appear as a solid precipitates or a clear solution depending upon the solubility of its ions. It is observed that all salts of Na, K, $\mathrm{N}{\mathrm{H}}_4$ are soluble. All nitrates and bicarbonates are also soluble. All halides (chlorides, bromides, iodides) are soluble except those of Ag, Hg (I) and Pb. All sulphates are soluble except those of Ag, Ca, Ba and Pb. Which one among the following combinations of solutions will produce a solid precipitate ?

1. A.Sodium sulphate and barium chloride
2. B.Magnesium sulphate and barium bicarbonate
3. C.Lithium iodide and barium chloride
4. D.Ammonium sulphate and potassium bromide

Iodized salt is a :

1. A.mixture of potassium iodide and common salt
2. B.mixture of molecular iodine and common salt
3. C.compound formed by combination of potassium iodide and common salt
4. D.compound formed by combination of molecular iodine and common salt

Which one among the following is a chemical process?

1. A.Distillation of sea (salty) water
2. B.Crystallization of impure salt (NaCl)
3. C.Production of iodine (${\mathrm{I}}_2$) from sea-weeds
4. D.Sublimation of iodine (${\mathrm{I}}_2$)

Two pieces of metallic wire having equal length and equal volume placed in air have different resistances. The two wires must :

1. A.have different cross sections
2. B.have different temperatures
3. C.be of different materials
4. D.be of same density

A hollow metal ball carrying an electric charge produces no electric field at points :

1. A.outside the sphere
2. B.on its surface
3. C.inside the sphere
4. D.only at the centre

A heavy ball is suspended as shown in the figure given above. A quick jerk on the lower string will break that string but a slow pull on the lower string will break the upper string. The first result occurs because :

1. A.the force is too small to move the ball
2. B.air friction holds the ball back
3. C.of action and reaction
4. D.the ball has inertia

Metal pipes used to carry water sometimes burst in the winter. This is because :

1. A.water expands when it freezes
2. B.metal contracts more than water
3. C.outside of the pipe contracts more than inside
4. D.metal expands more than water

Among the following elements, which one is essential for the transmission of impulses in the nerve fibre?

1. A.Calcium
2. B.Iron
3. C.Sodium
4. D.Zinc