Answer:
Alkali metal hydroxides can be used to test the identity of metals in certain salts. The colour of the precipitate will help identify the metal : Calcium hydroxide is soluble; no precipitate is formed.
Answer: The reaction is exothermic reaction as the energy of products is less than the energy of reactants.
Explanation: Exothermic reactions are defined as the reactions in which energy of the product is less than the energy of the reactants. The total energy is released in the form of heat and
for the reaction comes out to be negative.
Labeling of the parts in the diagram:
A represents the activation energy which is the energy required by reactants to cross the energy barrier to get converted to products.
E represents the potential energy of the reactants.
B represents the activated complex.
D represents the potential energy of the products.
C represents the total enthalpy change of the reaction, which comes out to be negative for exothermic reactions.

Lithium 6 would have 6 valence electrons in the outer orbital, while lithium 7 would have 7 in the outer orbital.
Answer:

Explanation:
We need to use the formula for heat of vaporization.

Identify the variables.
- The heat absorbed by the evaporating water is the <u>latent heat of vaporization. </u>For water, that is 2260 Joules per gram.
- Q is the energy, in this problem, 50,000 Joules.
- m is the mass, which is unknown.

Substitute the values into the formula.

We want to find the mass. We must isolate the variable, m.
m is being multiplied by 2260 J/g. The inverse operation of multiplication is division. Divide both sides by 2260 J/g.


Divide. Note that the Joules (J) will cancel each other out.


Round to the nearest whole number. The 1 in the tenth place tells us to leave the number as is.

The mass is about 22 grams, so choice B is correct.