Questions

True, Stress is a factor that contributes to heart disease risk.

More factors that contributes to heart disease risk are blood pressure, cholesterol, smoking, physical inactivity and overeating.

A genus can best be defined as a taxon composed of one or more species and a classification level lying below family.

Tractor was the single most important invention to farmers.

A gamma ray or gamma radiation, is a penetrating electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves and so imparts the highest photon energy.

Gamma rays are emanations that have neither mass nor charge.

Resistivity :

Resistivity is a measure of the resistance to the flow of electrons. 

Conductivity :

Conductivity is just the inverse of resistivity, σ = 1/ρ, where σ is conductivity and ρ is resistivity.

Example:

Think of a pipe and water, the bigger the pipe, the easier water can flow and thus the lower the resistance. 

An atom is composed of three subatomic particles. They are ::

1) Electron (-vely charged particle)

2) Proton (+vely charged particle)

3) Neutron (No charge particle)

Hence, Neutron is the subatomic particle which has no charge.

Piyush Goel