Isotopes of chlorine are ³⁵Cl and ³⁷Cl. Their atomic numbers are:
A. 17 and 20
B. 35 and 37
C. 17 and 17
D. 35 and 17
Answer: Option C
Solution (By JKSSB Mock Tests)
Atomic number is the number of protons, which is 17 for all chlorine atoms. Mass numbers differ due to different neutrons (18 and 20). Isotopes have same atomic number, different mass number.
Explanation:
Aluminium displaces iron from iron(III) oxide because Al is more reactive. This is a single displacement (or thermite) reaction. Also redox: Al oxidized, Fe reduced. Combination: one product; decomposition: one reactant.
Explanation:
Washing soda (sodium carbonate, Na₂CO₃) is used to remove permanent hardness of water. It reacts with soluble calcium and magnesium chlorides/sulfates to form insoluble carbonates, which can be filtered out. Baking soda, bleaching powder, and plaster of Paris do not have this water-softening capability.
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