Energy can be conserved by efficient energy use.
Answer: Option A
<u>Explanation:</u>
Energy can be transferred from one form to another, but it cannot be destroyed or created. So it can be conserved if efficiently used. Thus efficient usage of energy lead to conservation of energy. Due to conservation of energy, the forces can be renewable and non-renewable.
So, we should know how the input energy can be completely converted to another form of energy leading to efficient usage of energy without any loss. As if there is no loss, input energy will be equal to output energy leading to 100% efficiency.
Answer:
Xenon
Explanation:
Avogadro’s number represent the number of the constituent particles which are present in one mole of the substance. It is named after scientist Amedeo Avogadro and is denoted by
.
Avogadro constant:-

Let the molar mass of the element is x g/mol
So,
atoms have a mass of x g
Also,
atoms have a mass of
g
This mass is equal to 848 g
So,

x= 131.3 g/mol
This mass correspond to xenon.
Answer:
ΔH is negative and ΔS is negative.
Explanation:
Endothermic reaction -
The type of reaction in which energy is absorbed in the form of heat is known as endothermic reaction .
The reaction mixture usually get cooled after the reaction .( temperature decreases ) .
The sign of ΔH of an Endothermic reaction is positive .
<u>For the of process of freezing the liquid ethanol , energy in the form of heat is released and hence , exothermic reaction ΔH is negative .</u>
<u>In the process of freezing , liquid is converted to solid , i.e. , the randomness reduces , and hence , entropy also decreases , hence , ΔS is negative .</u>
Answer:

Explanation:
We are given a number of particles and asked to convert to moles.
<h3>1. Convert Particles to Moles </h3>
1 mole of any substance contains the same number of particles (atoms, molecules, formula units) : 6.022 *10²³ or Avogadro's Number. For this question, the particles are not specified.
So, we know that 1 mole of this substance contains 6.022 *10²³ particles. Let's set up a ratio.

We are converting 2.98*10²³ particles to moles, so we multiply the ratio by that value.

The units of particles cancel.



<h3>2. Round</h3>
The original measurement of particles (2.98*10²³) has 3 significant figures, so our answer must have the same.
For the number we found, 3 sig figs is the thousandth place.
The 8 in the ten-thousandth place (0.4948522086) tells us to round the 4 up to a 5 in the thousandth place.

2.98*10²³ particles are equal to approximately <u>0.495 moles.</u>