Answer:
The period 4 alkaline-earth metal has the name Calcium. An isotope of this element having 20 neutrons has a mass number of 40.
Explanation:
Looking at the periodic table 4th row for the alkaline-earth metal, we can find Calcium which has an atomic number of 20 (or protons number, or z). The mass number is given by the sum of protons and neutrons. If the number of protons in this case is 20 and the number of neutrons is also 20, the mass number A = 40.
Most of the surface of the earth is covered with water and looks blue from space.
Answer:
0.007 M
Explanation:
pH is defined as the negative logarithm of the concentration of hydrogen ions.
Thus,
pH = - log [H⁺]
The expression of the pH of the calculation of weak acid is:-
Where, C is the concentration = ?
Given, pH = 3.45
So, for 
, 
C = 0.007 M
Answer:
Substitution mutation
Explanation:
A substitution mutation is a type of mutation in which one or more nucleotide base is replaced by another in a sequence. This will result in the replacement of one or more amino acid in the amino acid sequence.
This is the case in this question where the original amino acid sequence was given as: Leucine – Alanine – Glycine – Leucine. After mutation, the following mutated sequence was produced: Leucine – Alanine – Valine – Leucine.
As illustrated above, one would notice that there is replacement of GLYCINE amino acid by VALINE in the mutated sequence, hence, it is an example of SUBSTITUTION MUTATION.
