Answer:
I dont know the first blank but I know the second one is groups and the last one is periods.
Answer:
Yes
Explanation:
A gene pool is the sum total of all the genes(sum of alleles)of a species and population at any given time is known as gene pool.
The new species are created in nature by four mechanisms such as geographic isolation (allopatric speciation), reproductive isolation (sympatric speciation), mating behaviour (parapatric speciation).
Due to any of these factors when population acquire unique changes in their genes and enough changes have been introduced in the gene pool of the population with time, two population become distinct from each other and not able to interbreed leads to the formation of new species.
C. Ca and Br because they're metals and nonmetals
Answer:
a compound,typically a crystalline one,in which water molecules are chemically bound to another compound or an element
