Answer: Barium is +2, Fluorine is -1
Explanation:
The charge of barium is +2, and the charge of fluorine is -1. You can determine this from the periodic table groups.
The formula for barium fluoride is thus BaF2.
Answer:
5×-10^8
That is the the scintific notation for 0.00000005
Answer=5×-10^8
Answer : This reaction is an exothermic reaction.
Explanation :
Endothermic reaction : It is defined as the chemical reaction in which the energy is absorbed from the surrounding.
In the endothermic reaction, the energy of reactant are less than the energy of product.
Exothermic reaction : It is defined as the chemical reaction in which the energy is released into the surrounding.
In the exothermic reaction, the energy of reactant are more than the energy of product.
Enthalpy of reaction : It is the difference between the energy of product and the reactant. It is represented as
.
The balanced chemical reaction will be:

From the reaction we conclude that the heat energy is released during the reaction that means this reaction is an exothermic reaction.
Hence, the reaction is an exothermic reaction.
C is the answer because he wants to know if less force is needed to pull on a slippery surface which reduces friction
we have
work done (W)= force(F) × displacemen(s)
or, 80= F× 8
or, F= 10 N
therefore, 10 N force is required to lift the rock.