The highest known element is-
(a) Oxygen
(b) Argon
(c) Helium
(d) Hydrogen
Oxygen is a chemical element that is a gas at room temperature and is essential for life.
When a liquid is heated fro 20°C to 60°C, its density-
(a) Remains the same
(b) Decreases
(c) Increases
(d) Is lost
When a liquid is heated from 20°C to 60°C, its density decreases.
The energy of an electron in the first Bohr orbit is-13.6eV, What will be its energy in the second Borh orbit?
(a) -6.8 eV
(b) -23.6 eV
(c) -12.8 eV
(d) -3.4 eV
E2= -13.6 ev*1/4= -13.6 eV/4= -3.4 eV
Which one of the following is an element?
(a) Graphite
(b) Glass
(c) Water
(d) Table salt
Elements are the simplest chemical substances, and all atoms of an element have the same number of protons, some examples of elements include: oxygen, hydrogen, carbon, nitrogen, iron, mercury, diamond, graphite, and chlorine.
Which one of the following is not a Metal?
(a) Platinum
(b) Mercury
(c) Silicon
(d) Nickel
Silicon is not a metal; it is considered a metalloid, which means it has properties of both metals and non-metals.