The grams of water produced is c
Answer:
- <em><u>A physical change has occurred, with no energy change.</u></em>
Explanation:
When a pencil lead is broken there is not change of any chemical properties, therefore it is not a chemical change, but just a physical change. In this case the change is just the number of pieces and dimensions.
Chemical changes always involve the formation of new different substances; the bonds between the atoms of the starting substances (reactants) breake and new bonds are formed leading to new substances (products) with different chemical composition (arrange of atoms). Chemical changes occur through chemical reactions.
Hence, if there is not change on the chemical composition, you think on physical changes. Physical changes include change in shape, size, state of matter (e.g. solid, liquid, gas). In the case of a pencil lead breaking, it is a change in shape and size.
Also, since energy has not been absorbed or released during the change, the energy of the pencil lead before having been broken is equal to the sum of the energies of the pieces of pencil lead obtained. So, this is a physical change with no energy changes.
Some examples of physical changes that include change in energy are the change of state (e.g. solid to liquid or liquid to gas) and the dissolution of a compound.
Answer:
AlN has highest melting point among given.
Explanation:
As per ionic model, ionic compounds are held together by electrostatic force. The ionic compound having strong electrostatic force will have high melting point.
Electrostatic force is proportional to charge and size of constituent ions.

In case of MgO
Charge on Mg = +2
Charge on O = -2

In case of LiF
Charge on Li = +1
Charge on F = -1

In case of AlN
Charge on Al = +3
Charge on N = -3

In case of RbF
Charge on Rb = +1
Charge on F = -1

In case of CaS
Charge on Ca = +2
Charge on S = -2

As magnitude of electrostatic force is highest in AlN, therefor, it has highest melting point.
Answer: 
Explanation:
According to Bronsted and Lowry an acid is a proton donor and base is a proton acceptor.
Therefore, the equation for the reaction will be as follows.

Here,
acts as a base as it is accepting a proton and
acts as an acid because it is donating a proton.