CHEMISTRY (Part-I) (Railway)

Total Questions: 50

21. Which of the following is the third member of the Dobereiner triad, that also features Lithium and Sodium? [RRB ALP & Technician Exam, 13.08.2018 Shift-I]

(1) Potassium
(2) Boron
(3) Barium
(4) Hydrogen

Correct Answer: (1) Potassium

Solution:According to Dobereiner, all elements occur in groups of three when arranged in increasing order of atomic masses. He referred to these groups as triads. In a triad, the elements have similar chemical properties. He placed alkali-forming elements lithium, sodium, and potassium in a triad.

22. Which of the following allotropes of Carbon is used as a reducing agent in metallurgy? [RRB ALP & Technician Exam,13.08.2018 Shift-III]

(1) Carbon Black
(2) Graphite
(3) Charcoal
(4) Coke

Correct Answer: (4) Coke

Solution:Coke is prepared by heating coal in the absence of air. Coke is an almost pure form of carbon. Coke is mainly used as a reducing agent in the extraction of metals (like iron, zinc etc.) Coke is used in the manufacture of steel. Coke is used in preparation of producer gas which is a mixture of carbon monoxide and nitrogen.

23. Two or more elements combine to form a: [RRB ALP & Technician Exam,13.08.2018 Shift-III]

(1) valency
(2) atom
(3) radical
(4) compound

Correct Answer: (4) compound

Solution:A compound is a substance formed when two or more chemical elements are chemically bonded together. The type of bonds holding elements together in a compound can vary: two common types are covalent bonds and ionic bonds. hydrogen ions as the unit above it. Hence in the given case, pH will be 5.

24. The pH of a solution, whose hydrogen ion concentration is 1 x 10⁻⁵ mole per litre, will be.

(1) 5
(2) 4
(3) 6
(4) 7
RRB ALP & Technician Exam, 13.08.2018 Shift-III

Correct Answer: (1) 5

Solution:The pH scale is a logarithmic one, meaning that each pH unit has 10 times as many hydrogen ions as the unit above it. Hence in the given case, pH will be 5.

25. Which of the following is NOT the combined form of carbon? [RRB ALP & Technician Exam, 13.08.2018 Shift-III]

(1) Chalk
(2) Marble
(3) Diamond
(4) Dolomite

Correct Answer: (3) Diamond

Solution:Diamond is a well known allotrope of carbon. Diamond is a form of carbon in which each carbon atom is covalently bonded to four other carbon atoms. This forms a strong, rigid, three-dimensional structure. The hardness and high dispersion of light by diamond makes it useful for both industrial applications and jewellery.

26. Which of the following is used for disinfecting drinking water? [RRB ALP & Technician Exam,13.08.2018 Shift-III]

(1) Washing soda
(2) Baking soda
(3) Baking powder
(4) Bleaching powder

Correct Answer: (4) Bleaching powder

Solution:Bleaching powder is added to drinking water for disinfection it because bleaching powder release free chlorine which kills the germs present in water. Chlorine kills pathogens such as bacteria and viruses by breaking the chemical bonds in their molecules.

27. Who stated the following law: The properties of the elements are the periodic function of their atomic masses? [RRB ALP & Technician Exam,13.08.2018 Shift-III]

(1) Moseley
(2) Newlands
(3) Mendeleev
(4) Dobereiner

Correct Answer: (3) Mendeleev

Solution:In 1869, Dmitri Ivanovich Mendeleev formulated a law, now known as the periodic law. The law is stated as follows. The properties of elements are periodic functions of their atomic masses. This means, if the elements are arranged in order of increasing atomic masses then those with similar properties are repeated at regular intervals.

28. Name the Russian chemist who stated that the properties of elements are a periodic function of their atomic masses? [RRB ALP & Technician Exam, 14.08.2018 Shift-I]

(1) Markovnikov
(2) Zelinsky
(3) Mendeleev
(4) Zaitsev

Correct Answer: (3) Mendeleev

Solution:Dmitri Mendeleev was a Russian chemist who developed the periodic classification of the elements. He stated that when all the known chemical elements were arranged in order of increasing atomic weight, the resulting table displayed a recurring pattern, or periodicity, of properties within groups of elements. He published the first recognizable periodic table in 1869.

29. Biogas is produced from biomass by: [RRB ALP & Technician Exam,14.08.2018 Shift-1]

(1) destructive distillation
(2) fractional distillation
(3) anaerobic fermentation
(4) dry distillation

Correct Answer: (3) anaerobic fermentation

Solution:Biogas refers to a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen (anaerobic fermentation). Biogas can be produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste or food waste. Biogas consists mainly of methane (CH₄) and carbon dioxide (CO₂).

30. Which of the following scientists had done some calculations for the fifth state of matter? [RRB ALP & Technician Exam,14.08.2018 Shift-I]

(1) Satyendra Nath Bose
(2) C.V. Raman
(3) Vikram Sarabhal
(4) Homi Bhabha

Correct Answer: (1) Satyendra Nath Bose

Solution:In 1920, an Indian scientist, Satyendra Nath Bose did some calculations for the fifth state of matter. On the basis of these calculations, Albert Einstein predicted the existence of a new state of matter called Bose-Einstein Condensate (BEC). The fifth state of matter was finally achieved by three scientists. Cornell, Ketterle and Wieman of USA by cooling a gas of extremely low density to super low temperatures.

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