Chemistry (Part-VI)

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

(a) Removal of acid from a molecule
(b) Removal of base from a molecule
(c) Removal of water from a molecule
(d) Removal of alkali from a molecule

Correct Answer: (c) Removal of water from a molecule

Solution:Removal of water from a molecule - Dehydration, in a chemical context, refers to the process of removing water molecules from a substance. This can occur through various chemical reactions.

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]

(a) Boiling
(b) Sublimation
(c) Transpiration
(d) Evaporation

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]

(a) Nitrous oxide
(b) Nitrogen Oxide
(c) Ammonia
(d) carbon dioxide

Correct Answer: (c) Ammonia

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]

(a) Liquid in liquid
(b) Solid in liquid
(c) Gas in solid
(d) Solid in Solid

Correct Answer: (a) Liquid in liquid

Solution:Liquid in liquid - An emulsion is a type of colloid where both the dispersed phase and the continuous phase are liquids. Examples include milk (fat in water) and mayonnaise (oil in vinegar).

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]

(a) Sieving
(b) sedimentation
(c) Yarning
(d) Threshing

Correct Answer: (b) sedimentation

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]

(a) Phosphorus
(b) Mercury
(c) Sodium
(d) Aluminium

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]

(a) Bromite
(b) Mercury
(c) Cadmium
(d) Glass

Correct Answer: (b) Mercury

Solution: Mercury - As mentioned above, mercury is unique among metals in that it exists in a liquid state at normal room temperature. Bromite is not a metal, cadmium is a solid metal, and glass is an amorphous solid.

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

(a) Gallium
(b) Zinc
(c) Calcium
(d) Magnesium

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:

None of the above - While gallium melts in the palm, it is not listed as an option. Potassium and sodium are highly reactive alkali metals and are typically stored under oil to prevent reaction with air and water. Magnesium and aluminium have high melting points.

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

(a) Waste water released from kitchen
(b) Waste water released from toilets
(c) Waste water released from factories
(d) Waste water released from hospitals

Correct Answer: (a) Waste water released from kitchen

Solution:Waste water released from kitchen - Sullage water generally refers to wastewater generated from domestic activities such as washing, bathing, and food preparation in kitchens and bathrooms, excluding sewage from toilets.