Answer:
atomic number of Be =4
electronic configuration :1s²2s²
but for Be2+ atomic number = 4-2 =2
electronic configuration : 1s²
Explanation:
Charges on both magnesium and oxygen is 2. Though opposite in sign, they have equal charges so, both of them will be cancelled by each other.
As a result, formula of magnesium oxide is MgO and not 
.
The student write the equation as 
, it is not correct.
Therefore, given equation will be balanced as follows.
Since, number of atoms on both reactant and product side are equal. Hence, this equation is completely balanced.
Answer:
D) both a and c are correct
Explanation:
The reaction rate is a measure of the speed of a chemical reaction. The factors that affects the rate of a chemical reaction are itemised below:
- Nature of the reactants
- Concentration of the reactants or pressure(if gaseous)
- Temperature
- Presence of catalyst
- Sunlight
Our concern here is temperature. Temperature affects a reaction considerably. Average kinetic energy is directly proportional to the temperature of the reacting particles. When the temperature of a reacting system is increase, the frequency of ordinary and effective collisions per unit time increases. A decrease in temperature implies that the number of collisions also decreases.
