Answer:
Reaction A, B, E and F are exothermic reactions.
Explanation:
Exothermic reactions are defined as the reactions in which energy of reactants is more than the energy of the products. In these reactions, energy is released by the system.
The total enthalpy of the reaction 
comes out to be negative.
Endothermic reactions are defined as the reactions in which energy of products is more than the energy of the reactants. In these reactions, energy is absorbed by the system.
The total enthalpy of the reaction comes out to be positive.
So, from the given option reaction which are exothermic are with negative value that enthalpy of reaction and those are:
1) 
,ΔH = -1203 kJ/mol
2)
,ΔH =-176 kJ/mol
3) 
,ΔH = -393.5 kJ/mol
4) 
,ΔH =-891 kJ/mol
Answer:
<em>The correct option is the structure in the option D. </em>
Explanation:
Ammonia contains a single nitrogen atom bonded to three hydrogen atoms.
The structure present in option A shows a single nitrogen atom bonded with a single hydrogen atom hence it is not correct.
The structure in option B shows a nitrogen atom bonded to four hydrogen atoms hence it is also not correct.
The structure in option C shows a nitrogen atom bonded to two hydrogen atoms hence it is also not correct.
The structure in option D shows a nitrogen atom bonded to three hydrogen atoms which is the correct structure of ammonia (NH3).
They have thier own group because because they have traits or metals and nonmetals
Answer:
The main function of water is to enhance the plant growth provide a permanent for species that live within it, or provide a temporary home or breeding ground for multiple amphibians, insects and water-birthed organismsand to provide the nutrients and minerals necessary to sustain physical life.
Answer:
B
Explanation:
to find the new rate when the concentration of reactants changes
