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Q1. (a) Define a chemical reaction.(b) What happens during a chemical reaction?(c) What do you understand by a chemical bond?Answer:(a) A chemical reaction is any alteration of matter that entails the creation of one or more compounds having wholly distinct characteristics.b) Chemical bonds between atoms or molecules are broken during chemical reaction clusters of atoms […]

Exercise: Q1. Define:(a) Matter(b) Intermolecular force of attraction.Answer:(a) Anything that has mass, takes up space and can be perceived by our senses is considered to be matter. Example: Air, book.(b) The molecules of matter are constantly moving and are held together by an attraction between them known as the intermolecular force of attraction. Q2. What […]

Exercise Q1. Define:(a) Radical(b) Valency(c) Molecular formulaAnswer:(a) Radical: An atom of an element or a collection of atoms from other elements that behave as a single unit and have a positive or negative charge on them is referred to as a radical.(b) Valency: The quantity of electrons that an atom’s valence shell contributes to or […]

EXERCISE Q1. Define: (a) a physical change, (b) a chemical change. Give two examples for the above changes.Answer:(a) A physical change is a temporary alteration in which the original substance’s does not change and its physical characteristics, such as colour, condition, shape, and size, may change. Example: Boiling of water, Melting of ice.(b) A chemical […]

Exercise 1. Fill in the blanks:(a) Hydrogen is __________ than air.(b) Hydrogen is __________ soluble in water.(c) Hydrogen bums with a __________ flame and __________ sound is heard.(d) A __________ hydrogen in the reactivity series gives hydrogen with water.(e) Hydrogen reacts with metal oxides to form __________ and __________.(f) Oxidation is the removal of __________ […]

Exercise – I Q1. Fill in the blanks.(a) __________ is present in both living and non-living things.(b) The tendency of an element to exist in two or more forms but in the same physical state is called __________.(c) __________ and __________ are the two major crystalline allotropes of carbon.(d) __________ is the hardest substance that […]

Exercise Q1. Fill in the blanks.(a) Dalton _ that atoms could not be divided(b) An ion which has a positive charge is called a _.(c) The outermost shell of an atom is known as _.(d) The _ of an atom is very hard and dense.(e) Neutrons are _ particles having mass equal to that of […]