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Chemistry (Part-VI)

📆 October 29, 2024

Total Questions: 50

31. What is dehydration? [S.S.C. Online CHSL (F-I) 30.01.2017]

Correct Answer: (c) Removal of water from a molecule
Solution:In chemistry and the biological sciences, a dehydration reaction is usually defined as a chemical reaction in which a water molecule is lost from the reaction molecule.

32. In the water cycle, snow and ice get directly converted into vapour. This process is called. [S.S.C. JE Mechanical Exam 22.03.2021]

Correct Answer: (b) Sublimation
Solution:In the water cycle, snow and ice are directly converted into vapor. This process is called sublimation. The process in which a solid substance on heating turns into a vapor without going into a liquid state and on cooling again becomes a solid without changing to a liquid state, is called sublimation. The following are some subliminal substances- Ammonium Chloride, Iodine, Camphor Naphthalene, etc.

33. Which of the following gases has the highest solubility in water at room temperature? [S.S.C. Online CHSL (T-I) 27.01.2017]

Correct Answer: (c) Nitrous oxide
Solution:Ammonia is highly soluble in water. About 30 grams of ammonia (NH₃) can be dissolved in 100 ml of water at 25 °C. The solution of ammonia in water is called ammonium hydroxide (NH₄OH).

34. An emulsion is a colloidal solution of: [S.S.C. Online Graduate Level (T-I) 6.09.2016]

Correct Answer: (a) Liquid in liquid
Solution:An emulsion is a colloidal solution of two or more immiscible liquids, in which one liquid remains as fine droplets in the other liquid. For example, milk is a solution or emulsion in which fat is dissolved in the form of an aqueous solution.

35. When the heavier component in a mixture settles after water is added to it, the process is called: [S.S.C. JE Mechanical Exam 22.03.2021]

Correct Answer: (b) Sedentation
Solution:

When a heavy component settles down after adding water to a mixture, this process is called 'sedimentation'. The components or particles that sit at the bottom during sedimentation are called 'sediment'. The conduction method is used to separate two components of a mixture whose sizes are different. The process of separating grains or grains from the stems of dried plants is called Threshing.

36. Which among the following elements is a liquid at room temperature? [S.S.C. Online CHSL (T-I) 7.01.2017]

Correct Answer: (b) Mercury
Solution:Mercury is the only metallic element that is found in the liquid state at normal temperature and pressure (or room temperature). Aluminium, phosphorus, and sodium remain in a solid state at room temperature.

37. Which metal remains in liquid form at normal temperature? [S.S.C. Online Stenographer 14.09.2017]

Correct Answer: (b) Mercury
Solution:Mercury is the only metallic element that is found in the liquid state at normal temperature and pressure (or room temperature). Aluminium, phosphorus, and sodium remain in a solid state at room temperature.

38. Which of the following metals will start melting when kept on the palm? [S.S.C. JE Mechanical Exam 27.10.2020]

Correct Answer: (a) Gallium
Solution:The atomic number of Gallium (Ga) is 31. It is soft and shiny in its pure state. It melts at normal temperature i.e. when kept on the palm. It is also used as semiconductor.

39. Which metal melts in the palm? [S.S.C. Online MTS (T-I) 19.09.2017]

Correct Answer: (e) None of the above
Solution:Gallium (Ga) is not found in nature in its pure form, but its compounds are found in small amounts in the minerals bauxite and zinc. Its melting point is about 30°C. This metal melts when placed on the palm.

40. Sullage water is__________. [S.S.C. Online Graduate Level (T-I) 29.08.2016]

Correct Answer: (a) Waste water released from kitchen
Solution:

The wastewater which comes out from the houses (except toilets) from the kitchen etc. is called 'sullage.

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