In chemistry, there are two types of change, they are chemical and physical changes. A chemical change is one in which new substance are formed and it is always irreversible while a physical change is one in which no new substance is formed and it is always reversible. There are many factors that can indicate that a chemical change has taken place, these include: energy transfer, formation of precipitation, gas production, etc. Fracture formation does not indicate chemical change. In fracture formation nothing changes, so it is a form of physical change.
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C. 7 is the pH scale of water.
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Explanation:
(A) Heavier members of group 1A are usually more reactive than the lighter members e.g. lithium react very slowly with liquid bromine whereas CS react violently.
Similarly Be of group 2A has smaller size, heavier member of this group show different colour in flame test but Be and Mg emit light when heated. Reactivity of group 2A metals decreases down the group
(B) In ethylene polymerization, the stronger catalytic action is shown by the alkyl of metal having less diameter e.g Be, Li etc.
A lithium alkyl in a hydrocarbon solvent is stereospecific catalyst for polymerisation of isoprene
