Could anyone please solve all these questions ACCURATELY for me please?

The observed value of the chi-squared statistic is (Q13) 

Under the null hypothesis, the smallest expected number of trees in any of the categories is (Q14)  so, under the null hypothesis, the probability histogram of the chi-squared statistic (Q15)   ? A: is not B: is  approximated well by a chi-squared curve.

The appropriate chi-squared curve to use to approximate the probability histogram of the chi-squared statistic has (enter a number) (Q16)  degrees of freedom.

The P-value of the null hypothesis is approximately (Q17) 

Should the null hypothesis be rejected at significance level 5%? (Q18)   ? A: no B: yes