There are 30 protons and 39 neutrons in the nucleus.
This must me the isotope of an element with an atomic mass close to 69 u.
The only candidates are Zn and Ga.
Zn has a zinc-69 isotope with mass 68.926 u.
Ga has a gallium -69 isotope with mass 68.925 u.
The isotope is probably

.
It has 30 protons and 39 neutrons.
Answer:
Science is the study of the physical or material world. Science is important because it can answer questions about new ideas and can advance technologies
Explanation:
Answer: d) -705.55 kJ
Explanation:
Heat of reaction is the change of enthalpy during a chemical reaction with all substances in their standard states.

Reversing the reaction, changes the sign of 


On multiplying the reaction by
, enthalpy gets half:


Thus the enthalpy change for the given reaction is -705.55kJ
Answer:
Burning of paper is not a physical change.It is chemical change as ash is formed in the process which is new compound and oxides of carbon are also released during the process!
Answer: Endothermic reaction.
Explanation: A chemical reaction in which energy is absorbed from the surrounding environment.