Answer:When a substance undergoes a chemical change some of the chemical changes can be reversed with a chemical change.
Explanation:
A chemical change changes all of the element but some chemical changes but very few can be changed back to its original substance only with a chemical change.
Answer: Option (b) is the correct answer.
Explanation:
It is known that metals are the species which readily lose an electron and tend to attain a positive charge.
For example, atomic number of sodium is 11 and its is an alkali metal. It electronic distribution is 2, 8, 1.
And, in order to attain stability it readily loses an electron and thus it become
ion.
Also, it is known that species which tend to transfer or donate their valence electrons to other atoms tend to form ionic bond and the compound formed is known as ionic compound.
Therefore, we can conclude that the statement metal atoms held together by ionic bonds best describes a metal solid.
Answer:
Positron emission
Explanation:
Positron emission involves the conversion of a proton to a neutron. This process increases the mass number of the daughter nucleus by 1 while its atomic number remains the same. The new neutron increases the number of neutrons present in the daughter nucleus hence the process increases the N/P ratio.
A positron is usually ejected in the process together with an anti-neutrino to balance the spins.
<span> UV radiation are high energy radiations and they are mutation causing agents so
</span>Mutagen <span> best describes the relationship of solar UV radiation to the environment
so option A is correct
hope it helps</span>
The pressure at the bottom : 19600 N/m²
<h3>Further explanation</h3>
Given
A ground water tank has its height 2m
Required
The pressure at its bottom
Solution
Hydrostatic pressure is the pressure caused by the weight of a liquid.
The weight of a liquid is affected by the force of gravity.
The hydrostatic pressure of a liquid can be formulated:

Ph = hydrostatic pressure (N / m², Pa)
ρ = density of liquid (kg / m³)
g = acceleration due to gravity (m / s²)
h = height / depth of liquid surface (m)
ρ = density of water (kg / m³) = 1000
g = acceleration due to gravity = 9.8 m/ sec²
The pressure
