Answer:
Null Hypothesis - 
The observed frequency is approximately equal to the expected frequency of phenotype. 
Step-by-step explanation:
Pure Breeding Cross - TTww x ttWW
Genotype of offspring in F2 generation - TtWw
Null Hypothesis - 
The observed frequency is approximately equal to the expected frequency of phenotype. 
The chi square analysis is attached 
The degree of freedom for this question is 3
The p value for X^2 estimated through chi square test is 0.5
Hence the null hypothesis is accepted.