Atmospheric Pollution — CHEMISTRY STD 9 — Question

Atoms have a central core called…Nucleus.. which is surrounded by __________

The second and the third periods have ________elements and are called ________periods.

Sodium ………………. reacts smoothly with cold water.
(metal, amalgam, in the molten state)

The temperature on the Kelvin scale at which molecular motion completely ceases is called……………

If the temperature is reduced to half, ………….. would also reduce to half.

Noble ________ are placed in ________group in the last ________of the periodic table.

Isotopes have different _________ number, because their nuclei contain different number of _________

________metals and alkaline ________metals are placed in groups 1A and ________respectively on the left band side of periodic table.

A metal …………….. hydrogen in the activity series gives hydrogen with …………… acid or …………… acid.
(above, below, dilute hydrochloric, concentrated hydrochloric, dilute sulphuric).

The central part of an atom holding __________ charged parities and neutral __________ called nucleus.