Having freckles is dominant (F) and not having freckles is recessive (f), A mother has Ff and a father has Ff , if they have a child which genotype will make the child have freckles

For the child to have freckles his genotype must be FF of Ff

Explanation:

Since freckles is dominant (F) and not having freckles is recessive (f), If the child has a genotype with at least one dominant gene (that is FF, Fr) , the child would have freckles but for the child not to have freckles, the genotype gene must both be recessive (that is ff)

Since the other has Ff and a father has Ff, if they have four children, the children genotypes would be FF, Ff, Ff and ff. Since freckles (F) is dominant for the child to have freckles his genotype must be FF of Ff

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-

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