A liquid requires enthalpy of vaporization to transform into vapor or gas at its boiling point. Here the element absorbs heat from surroundings or heat source.
This energy is used in breaking the forces of attraction among the atoms and molecules of the element. The molecules get separated to higher distances. The energy is converted in to the kinetic energy of the molecules in gaseous form and into the internal energy in terms of the temperature of the gas.
Eight electrons surrounding each non-hydrogen atom is the optimal electronic arrangement for covalent molecules because it is needed to achieve an octet structure and is necessary to fill both the s and p subshells of electrons.
<h3>What is Covalent bonding?</h3>
This is the type of bonding which involves the sharing of electrons between atoms of an element.
This is done to achieve an octet configuration thereby making them stable and less reactive thereby making it the most appropriate choice.
Read more about Covalent bonding here brainly.com/question/3447218
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The question is incomplete, the complete question is;
The compound magnesium phosphate has the chemical formula Mg3(PO4)2. In this compound, phosphorus and oxygen act together as one charged particle, which is connected to magnesium, the other charged particle. What does the 2 mean in the formula 5Mg3(PO4)2? A. There are two elements in magnesium phosphate. B. There are two molecules of magnesium phosphate. C. There are two magnesium ions in a molecule of magnesium phosphate. D. There are two phosphate ions in a molecule of magnesium phosphate.
Answer:
There are two phosphate ions in a molecule of magnesium phosphate.
Explanation:
The compound magnesium phosphate is an ionic compound. Ionic compounds always consists of two ions, a positive ion and a negative ion.
In this case, the positive ion is Mg^2+ while the negative ion is PO4^3-.
The subscript, 2 after the formula of the phosphate ion means that there are two phosphate ions in each formula unit of magnesium phosphate.
Given :
The focal length of a concave mirror is 18 cm.
To Find :
The radius of curvature of the concave mirror.
Solution :
We know,
Therefore, the radius of curvature of concave mirror is 36 cm.
Hence, this is the required solution.
Answer:
Time taken, 
Explanation:
It is given that, a small metal ball is suspended from the ceiling by a thread of negligible mass. The ball is then set in motion in a horizontal circle so that the thread’s trajectory describes a cone as shown in attached figure.
From the figure,
The sum of forces in y direction is :
Sum of forces in x direction,
.............(1)
Also, 
Equation (1) becomes :
...............(2)
Let t is the time taken for the ball to rotate once around the axis. It is given by :
Put the value of T from equation (2) to the above expression:
On solving above equation :
Hence, this is the required solution.
