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The reaction in which two compounds exchange their ions to form two new compounds is called (1) Displacement reaction (2) Combination reaction (3) Double displacement reaction (4) redox reaction

Answer: (3) Double displacement reaction When a component of two ionic compounds is exchanged and two new components are made, double... View Article

Rancidity can be prevented by (1) Adding antioxidants (2) Storing food away from light (3) Keeping food in the refrigerator (4) All of these.

Answer: (4) All of these Rancidity is a very particular term that refers in the most general way to the spoilage of food in such a way that it... View Article

In which of the following, heat energy will be evolved? (1) Electrolysis of water (2) Dissolution of NH4Cl in water (3) Burning of L.P.G. (4) Decomposition of AgBr in the presence of sunlight

Answer: (3) Burning of L.P.G. Fuels release heat on burning. Heat of combustion is total amount of heat released when a fuel is burnt when there... View Article

When a magnesium ribbon is burnt in air, the ash formed is (1) Black (2) White (3) Yellow (4) Pink

Answer: (2) White When magnesium ribbon is burnt in air, it combines with oxygen to form white powder magnesium oxide (MgO) with the release of... View Article

Dilute hydrochloric acid is added to granulated zinc taken in a test tube. The following observations are recorded. Point out the correct observation. (a) The surface of metal becomes shining (b) The reaction mixture turns milky (c) Odour of a pungent-smelling gas is recorded (d) A colourless and odourless gas is evolved.

Answer: (d) A colourless and odourless gas is evolved. A colourless and odourless gas is produced with bubbles when diluting hydrochloric acid... View Article

Why do fireflies glow at night?

Answer: Inside their bodies, fireflies create a chemical reaction that causes them to emit light. This kind of light emission is known as... View Article

When crystals of lead nitrate are heated strongly in a dry test tube (1) Crystals immediately melt (2) Brown residue is left (3) White fumes appear in the tube (4) Yellow residue is left

Answer: (4) Yellow residue is left The evolution of brown gas, nitrogen dioxide, and a yellow residue of lead oxide results from strong heating... View Article

A silver article turns black when kept in the open for a few days due to the formation of (1) H2S (2) AgS (3) AgSO4 (4) Ag2S

Answer: (4) Ag2S When placed in the air, the silver object turns black because the silver element reacts with sulphur compounds such as H2S... View Article

In the decomposition of lead (II) nitrate to give lead (II) oxide, nitrogen dioxide and oxygen gas, the coefficient of nitrogen dioxide in the balanced equation is (1) 1 (2) 2 (3) 3 (4) 4

Answer: (4) 4 A decomposition reaction can be characterized as a type of chemical reaction in which one single compound splits into several... View Article

The electrolytic decomposition of water gives H₂ and O₂ in the ratio of (1) 1: 2 by volume (2) 2: 1 by volume (3) 8: 1 by mass (4) 1: 2 by mass

Answer: (2) 2 : 1 by volume The number of molecules formed by hydrogen is twice the number of molecules generated by oxygen. Therefore, water... View Article

Which of the following gases can be used for storage of fresh sample of oil for a long time? (1) Carbon dioxide or oxygen (2) Nitrogen or oxygen (3) Carbon dioxide or helium (4) Helium or nitrogen

The correct answer is (4) Helium or nitrogen Oxygen acts as an oxidizing agent. Nitrogen is less reactive than helium, and is most commonly... View Article

Choose the forms in which most plants absorb nitrogen (i) Proteins (ii) Nitrates and Nitrites (iii) Urea (iv) Atmospheric nitrogen. Choose: (1) (i) and (ii) (2) (ii) and (iii) (3) (iii) and (iv) (4) (i) and (iv)

Answer: (2) (ii) and (iii) Nitrogen is an essential nutrient for plant growth, development, and reproduction. The biological method occurs in... View Article

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Archives

The reaction in which two compounds exchange their ions to form two new compounds is called (1) Displacement reaction (2) Combination reaction (3) Double displacement reaction (4) redox reaction

Rancidity can be prevented by (1) Adding antioxidants (2) Storing food away from light (3) Keeping food in the refrigerator (4) All of these.

In which of the following, heat energy will be evolved? (1) Electrolysis of water (2) Dissolution of NH4Cl in water (3) Burning of L.P.G. (4) Decomposition of AgBr in the presence of sunlight

When a magnesium ribbon is burnt in air, the ash formed is (1) Black (2) White (3) Yellow (4) Pink

Why do fireflies glow at night?

When crystals of lead nitrate are heated strongly in a dry test tube (1) Crystals immediately melt (2) Brown residue is left (3) White fumes appear in the tube (4) Yellow residue is left

A silver article turns black when kept in the open for a few days due to the formation of (1) H2S (2) AgS (3) AgSO4 (4) Ag2S

In the decomposition of lead (II) nitrate to give lead (II) oxide, nitrogen dioxide and oxygen gas, the coefficient of nitrogen dioxide in the balanced equation is (1) 1 (2) 2 (3) 3 (4) 4

The electrolytic decomposition of water gives H₂ and O₂ in the ratio of (1) 1: 2 by volume (2) 2: 1 by volume (3) 8: 1 by mass (4) 1: 2 by mass

Which of the following gases can be used for storage of fresh sample of oil for a long time? (1) Carbon dioxide or oxygen (2) Nitrogen or oxygen (3) Carbon dioxide or helium (4) Helium or nitrogen

The chemical formula of lead sulphate is (1) Pb₂SO₄ (2) Pb (SO₄)₂ (3) PbSO₄ (4) Pb₂(SO₄)₃

Give reasons why plant and animals depend on each other?

One lakh eight thousand how can right in numbers?

The reciprocal of 1 is ___________?

What is the taste of lemon, sugar, curd, lime, baking soda, amla, tamarind, raw mango, pomegranate, water?

Prove that (sec A + tan A) (1 – sin A) = cos A

Each edge of a cube is increased by 50%. Find the percentage increase in the surface area of the cube.

Give some examples of each monocot and dicot seeds.

Choose the forms in which most plants absorb nitrogen (i) Proteins (ii) Nitrates and Nitrites (iii) Urea (iv) Atmospheric nitrogen. Choose: (1) (i) and (ii) (2) (ii) and (iii) (3) (iii) and (iv) (4) (i) and (iv)