The Language of Chemistry — CHEMISTRY STD 9 — Question

Name a metal which displaces hydrogen very slowly from dilute HCL.

From the standpoint of atomic structure, what determines which elements will be the first and which the last in a period of the periodic table?

How does the percentage of oxygen in the atmosphere remain constant, inspite of the fact that a large amount of it is used tor combustion and respiration?

In which of the following substances will there be
No change in mass when they are exposed to air?
Sodium chloride
Iron
Conc. sulphuric acid
Table salt
Sodium carbonate crystals

Give the name of the element and number of atom of those elements present in the following compound.
Ammonium dichromate

Explain why:
Boiled or distilled water tastes flat.

An element A has 2 electrons in its fourth shell. State:
is it anoxidisingor reducing agent

The molecular theory states that the pressure exerted by a gas in a closed vessel results from the gas molecules striking against the walls of the vessel. How will the pressure change if

1. The temperature is doubled keeping the volume constant
2. The volume is made half of its original value keeping the T constant

What are the following group known as?
Group 1