Answer: The missing coefficient is 2.
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

As in the products, there are 2 atoms of sodium, thus there will be 2 atoms of of sodium in the reactant as well. This will balance the number of hydrogen and oxygen atoms as well.
Thus the missing coefficient is 2.
Jasmine have 20 fish because4 times 5 equals 20
<span>Find
the speed of the car in which it travels at 150 km in 7200 seconds.
This is an easy question, you just need to follow the given formula as always.
Since the time and the distance is already given, we are now looking for the speed
=> time = 7200 seconds
=> distance = 150km</span><span>
d = speed x time
S = distance / time
s = 150 km / 7200 seconds
s = 0.021 km / seconds.
Thus, the car travels for about 0.021 km per seconds.
</span>
Chlorine has a charge -1. It means that X is +2 so that the formula is XCl2. Group 2 is the correct answer.
“Water” is the best thermal insulator.
Option: B
<u>Explanation</u>:
“Thermal insulators” are the materials which do not allow heat to transfer. “Water” is the substance which does not transfer heat. Hence, the “water” is the best “thermal insulator”. Water is the bad conductor of thermal heat. Water has “low thermal conductivity” than other substances, so this acts as an insulator as long as it is not traveled from one place to another. Heat is transferred when a “hot object collides” with “the cold objects”. The “thermal conductivity” of “water” is 0.6 W/m K.