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Where do we apply a force while walking?

Answer: While walking, we apply a force on the ground, which causes the ground to apply a reaction force on our foot, allowing us to move... View Article

Which of the following can be beaten into thin sheets? (a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen

Answer: (a) Zinc Metals are minerals or substances that form naturally below the surface of the Earth. Most metals are lustrous or shiny. Metals... View Article

Which of the following cannot be charged easily by friction? (a) A plastic scale (b) A copper rod (c) An inflated balloon (d) A woollen cloth.

Answer: (b) A copper rod Friction is defined as the resistance offered by the surfaces that are in contact with each other when they move over... View Article

Which of the following contains maximum number of molecules? (a) 1g CO₂ (b) 1g N₂ (c) 1g H^{2 (d) 1g CH₄}

Answer: (c) 1g H2 NA = 6.023×1023 ⇒ (1/44) x 6.022 x 1023 = 1.368 x 1022 molecules ⇒ (1/28) x 6.022 x 1023 = 2.15 x 1022... View Article

Which of the following correctly represents 360 g of water? (i) 2 moles of H₂0 (ii) 20 moles of water (iii) 6.022 × 10²³ molecules of water (iv) 1.2044×10²⁵ molecules of water Choose the option : (a) (i) (b) (i) and (iv) (c) (ii) and (iii) (d) (ii) and (iv)

Answer: (d) (ii) and (iv) One mole of a substance is equal to the substance’s 6.022 x 1023 units. The 6.022 x 1023 number is known as the... View Article

Which of the following expressions are polynomials in one variable and which are not? State reasons for your answer. (i) 3√t + t√2 (ii) y + 2/y (iii) x¹⁰ + y³+t⁵⁰

Answer: A polynomial is defined as an expression that is composed of variables, constants and exponents, that are combined using mathematical... View Article

Which of the following expressions are polynomials in one variable and which are not? State reasons for your answer. (i) 4x²–3x+7 (ii) y²+√2

Answer: A polynomial is defined as an expression that is composed of variables, constants and exponents, that are combined using mathematical... View Article

Which of the following figures depicts the position of pole star correctly?

Answer: (a) The polar star is the biggest of all-stars and will be the first star to rise after sunset in the sky. It rises in the north and is... View Article

Which of the following has maximum number of atoms? (a) 18g of H₂O (b) 18g of O₂ (c) 18g of CO₂ (d) 18g of CH₄

Answer: (d) 18g of CH4 Number of atoms = Mass of substance × Number of atoms in the molecule/ Molar mass × NA NA = 6.023×1023 ⇒ 18 x 3/18 ×... View Article

Which of the following is not likely to cause Tsunami? (a) A major nuclear explosion undersea (b) Earthquake (c) Volcanic eruption (d) Lightning

Answer: (d) Lightning Tsunamis are caused by a disturbance deep under the surface of the water. Lightening will not harm the sea, but... View Article

Which of the following metals is used in electroplating to make objects appear shining? (a) iron (b) copper (c) chromium (d) aluminium

Answer: (c) chromium Electroplating is the process of aligning another metal onto metal. This is accomplished using an electroplating apparatus... View Article

Which of the following solutions will not make the bulb in Fig glow? (a) sodium chlorides (b) copper sulphate (c) silver nitrate (d) sugar solution in distilled water

Answer: (d) sugar solution in distilled water In diluted water, sugar solution does not produce free ions. As a result, it is regarded as a poor... View Article

Which of the following statements are correct? (i) Sound is produced by vibrations. (ii) Sound requires a medium for propagation. (iii) Light and sound both require a medium for propagation. (iv) Sound travels slower than light. (a) i & ii only (b) i, ii & iii only (c) ii, iii & iv only (d) i, ii & iv only

Answer:(d) i, ii & iv only Although light may travel in a vacuum, only sound requires a medium to travel. Sound needs a material medium for... View Article

Which of the following statements is correct regarding rods and cones in the human eye? (a) Cones are sensitive to dim light. (b) Cones are sensitive to bright light. (c) Rods are sensitive to bright light. (d) Rods can sense colour.

Answer: (b) Cones are sensitive to bright light. Cones sense colour because they are sensitive to bright light, whereas rods are sensitive to low... View Article

Which of the following statements is correct? (a) All metals are ductile. (b) All non-metals are ductile. (c) Generally, metals are ductile. (d) Some non-metals are ductile.

Answer: (c) Generally, metals are ductile. Ductility is a quality that allows a substance to be pulled into thin wires. Most metals are ductile,... View Article

Which of the following statements is incorrect? (a) Friction acts on a ball rolling along the ground. (b) Friction acts on a boat moving on water. (c) Friction acts on a bicycle moving on a smooth road. (d) Friction does not act on a ball moving through air.

Answer: (d) Friction does not act on a ball moving through air. Friction acts on a body moving in the air as fluid friction Friction is caused... View Article

Which of the following statements is not correct? (i) Forests protect the soil from erosion. (ii) Plants and animals in a forest are not dependent on one another. (iii) Forests influence the climate and water cycle. (iv) Soil helps forests to grow and regenerate.

Answer: (ii) Plants and animals in a forest are not dependent on one another. This is due to the fact that plants and animals rely on one another... View Article

Which of the following statements is not true about an atom? (a) Atoms are not able to exist independently (b) Atoms are the basic units from which molecules and ions are formed (c) Atoms are always neutral in nature d) Atoms aggregate in large numbers to form the matter that we can see, feel or touch

Answer: (a) Atoms are not able to exist independently It is not true that atoms cannot exist independently. Atoms of most elements cannot exist... View Article

Which of the following would weigh the highest? (a) 0.2 mole of sucrose (C¹²H²² O¹¹) (b) 2 moles of CO² (c) 2 moles of CaCO³ (d) 10 moles of H²O

Answer: (c) 2 moles of CaCO3 The molecular mass of C12H22O11 Carbon = 12 Hydrogen = 1 Oxygen = 16 C12H22O11 = 12(12) + 22(1) + 11(16) gm... View Article

Which of the statements given below is correct? (i) In winter the winds flow from the land to the ocean. (ii) In summer the winds flow from the land towards the ocean. (iii) A cyclone is formed by a very high-pressure system with very high-speed winds revolving around it. (iv) The coastline of India is not vulnerable to cyclones.

Answer: (i) In winter, the winds flow from the land to the ocean. The wind is an air movement having both direction and speed. It is made up of... View Article

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