Each of the models shown represents a magnesium atom. Which models show the same isotope of magnesium? P, Q, and R P and Q

P and R

Q and R

P and Q

Q and R

Explanation:

To begin, we must bear in mind the meaning of isotope.

Isotopes are atoms having the same atomic number (i.e proton) but different mass number due to the difference in the neutron number present in the atoms involved.

Thus, we shall write out the number of protons, neutrons and electrons present in the model given above. This is given:

Model P:

Proton = 12

Neutron = 13

Electron = 13

Model Q:

Proton = 12

Neutron = 12

Electron = 13

Model R:

Proton = 12

Neutron = 13

Electron = 12

From the above data, we can say that:

1. P and Q are isotope since they have different Neutron number.

2. P and R are not isotope since they have the same Neutron number.

3. Q and R are isotope since they have different Neutron number.

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.

gas

explanation:

smoke is the matter of a gas