General Knowledge (Part-B: English) NDA/NA SOLVED PAPER 2021-II (51 to 100)

Total Questions: 50

31. The pH value of Milk of Magnesia is approximately

Correct Answer: (c) 10
Solution:Milk of magnesia is a medication used to treat heartburn, upset stomach, and constipation. It is also a chemical solution, and its acidity level can be measured using the pH scale. The pH value of Milk of Magnesia is 10. Milk of magnesia's chemical name is Magnesium hydroxide. It is a base.It is used to neutralize the excess acid in the stomach.
Note: The answer key, however, mentions 10 as the answer, so it can be taken as nearest to the exact value.

32. Which one of the following compounds is used in 'black and white' photography?

Correct Answer: (e) Both (b) & (c)
Solution:(b/c) Silver salts, such as silver bromide and silver chloride, are used in black and white photography; thus, both option (b) and option (c) are correct.

33. What is the number of water molecules present in a Ferrous Sulphate crystal?

Correct Answer: (d) 7
Solution:Ferrous sulphate crystals contain 7 water molecules, known as the water of crystallization. The formula is FeSO4.7H2O. When crystals of ferrous sulphate are heated it loses water of crystallisation and changes their colour. On further heating ferrous sulphate decomposes to ferric oxide with the evolution of two gases containing sulphur.

34. What is the colour of the precipitate obtained by passing CO₂, gas through lime water?

Correct Answer: (c) White
Solution:Carbon dioxide reacts with limewater (a solution of calcium hydroxide, Ca (OH)₂), to form a white precipitate (appears milky) of calcium carbonate, CaCO₃. Adding more carbon dioxide results in the precipitate dissolving to form a colourless solution of calcium hydrogen carbonate.

35. Which one of the following pairs of elements is liquid at room temperature and at normal pressure?

Correct Answer: (b) Mercury and Bromine
Solution:Bromine and mercury are the two elements that remain liquid at room temperature and standard pressure. Two elements are liquid at the temperature technically designated "room temperature" or 298 K (25°C) and a total of six elements that can be liquids at actual room temperatures and pressures. There are eight liquid elements if you include recently-discovered synthetic elements. Room temperature is a loosely defined term that can mean anywhere from 20°C to 29°C. For science, it's usually considered to be either 20°C or 25°C.

36. Which one of the following methods can be used to separate anthracene from a mixture of salt and anthracene?

Correct Answer: (b) Sublimation
Solution:To separate a mixture of anthracene and salt, we can use the process of sublimation. Sublimation is the transition of a substance directly from the solid to the gas state without passing through the intermediate liquid state.

37. Shoots of plant show upward movement and it can be designated to be

Correct Answer: (d) Negatively geotropic
Solution:Geotropism is the growth of the parts of plants in response to the force of gravity. The upward growth of plant shoots is an instance of negative geotropism; the downward growth of roots is positive geotropism.

38. Which one of the following statements about the process of photosynthesis is correct?

Correct Answer: (c) Water molecule splits into hydrogen and oxygen.
Solution:During photosynthesis, water molecules split into hydrogen and oxygen in a process known as photolysis; thus, option (c) is correct.

39. How are evergreen plants with woody stems having naked seed classified?

Correct Answer: (d) Gymnosperms
Solution:Gymnosperms are mostly evergreen, perennial and woody. Their stems are generally without branches. Gymnosperms are plants with naked seeds. There are about 650 living species of gymnosperm plants.

40. Which one of the following tissues is known as basic packing tissue and found in xylem and phloem?

Correct Answer: (b) Parenchyma
Solution:Parenchyma tissues are known as basic packing tissue and are found in the xylem and Phloem. There are different types of parenchyma tissues, Spongy mesophyll tissues are present below the layers of palisade tissues. 'Ray parenchyma' tissue is present in wood rays. Parenchyma tissue occurs in the xylem and phloem of 'vascular bundles'.