Science [1 Mark Questions]

A balanced chemical equation is one in which the total number of atoms of any element on the reactant side is equal to die total number of atoms of that element on the product side.

The total number of protons and neutrons present in the nucleus of an atom is called as mass number.

The total number of protons present in the nucleus of an atom is called its atomic number.

The total number of protons present in an atom is equal to the total number of electrons, thus balancing the total charge of the atom.

When invisible radiation falls on materials like zinc sulphite, they emit a visible light (or glow). These materials are called fluorescent.

Positive valency and negative valency.

Product is the substance that are formed in a chemical reaction.

Reactant is the substance that take part in a chemical reaction.

The nucleus is the central dense core of the atom consisting of neutrons and protons.

Proton, electron and neutron.

Electrons revolve around the nucleus in a circular fixed paths is called orbits or shells.

The arrangement of electrons in the orbits is known as electronic configuration.

Neutron is a neutral particle, that is it carries no charge.

When electricity passes through air, remove the electrons*from the gaseous atoms and produces ions. This is called electrical discharge.

Atom is the smallest particle of matter that takes part in a chemical reaction.

J.J. Thomson found that cathode rays were attracted by the positively charged plate and repelled by the negatively charged plate. This led him to the conclusion that the cathode rays (electrons) were made of negatively charged particles.

It is because the small particles of the cathode rays (electrons) have mass and energy. This energy is used in rotating the paddle wheels.

A chemical equation is a short hand representation of a chemical reaction with the help of chemical symbols and formulas.

An atom or a group of atoms when they either lose or gain electrons, get converted into ions or radicals.

The valency of an element is defined as the number of hydrogen atoms which combine with one atom of it.

The Law of constant proportions states that in a pure chemical compound the elements are always present in definite proportions by mass.