What is the phenotypic and genotypic ratio in a monohybrid test cross?

In the $F_2$ generation of a Mendelian monohybrid cross,how many individuals retain the parental genotypes (in $\%$)?

When the $F_1$ hybrid $Tt$ is crossed with the recessive parent $tt$,it is a case of....

$A$ heterozygous tall plant is crossed with a dwarf plant. The proportion of dwarf plants in the offspring will be: (in $\%$)

If two pea plants with red flowers,whose genotypes are unknown,are crossed,$75\%$ of the offspring have red flowers and $25\%$ have white flowers. The genotypes of the red-flowered parent plants must be:

$A$ true-breeding plant producing red flowers is crossed with a pure-breeding plant producing white flowers. The allele for the red color of the flower is dominant. After selfing the plants of the first filial $(F_1)$ generation, the proportion of plants producing red and white flowers in the progeny would be: