Chemistry
Write 'true' or 'false' for the following and correct the false statements.
(a) When an atom gains one or more electrons, it becomes positively charged.
(b) The valency of nitrogen in ammonia gas is 3.
(c) The sulphide ion is a polyatomic ion.
(d) The nitrate ion is represented as NO2-.
(e) The element cobalt is represented as CO.
Valency
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Answer
(a) False
Correct Statement — When an atom gains one or more electrons, it becomes negatively charged.
(b) True
(c) False
Correct Statement — The sulphide ion (S2-) is a monoatomic ion.
(d) False
Correct Statement — The nitrate ion is represented as NO3⁻.
(e) False
Correct Statement — The element cobalt is represented as Co.
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Related Questions
Assertion (A): A chemical equation is the symbolic representation of a chemical reaction using symbols and formulae of the substances involved in the reaction.
Reason (R): Every chemical equation needs to be balanced to follow the law of conservation of mass.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Fill in the blanks:
(a) A symbol represents …………… of an element.
(b) An atom is neither created nor destroyed during a …………… .
(c) …………… are positively charged ions.
(d) Total number of atoms of all the elements present in Al2O3 is …………… .
(e) A …………… is the symbolic representation of a chemical reaction using symbols and formulae of the substances taking part in the reaction.
Match the following:
Column A Column B (a) Combining capacity of an element (i) Silicon dioxide (b) The radical/ion formed due to the loss of electrons (ii) Molecular formula (c) Symbolic representation of a compound (iii) Calcium carbonate (d) Marble (iv) Valency (e) Sand (v) Cation Name the following:
(a) A polyatomic positive ion.
(b) The substances written on the left side of an arrow in an equation.
(c) The substances which are formed during a chemical reaction.
(d) An unbalanced chemical equation.
(e) An atom or group of atoms that behave as a single charged unit.
(f) A substance used to increase the rate of reaction.