Which event in the chromosomal structure leads to the formation of a syndrome?

Down syndrome is caused by an extra chromosome in the $21$st pair. What percentage of offspring from an affected mother and a normal father will show the effect of this disorder (in $\%$)?

Down syndrome is caused by an extra copy of chromosome $21$. If an affected mother and a normal father produce offspring,what percentage of the offspring will be affected by this disorder (in $\%$)?

An abnormal human baby with $XXX$ sex chromosomes was born due to

$A$ man having Klinefelter's syndrome is

Match the Column $I$ with Column $II$:

Column $I$	Column $II$
$(A)$ Autosomal trisomy	$(i)$ Turner's Syndrome
$(B)$ Allosomal trisomy	$(ii)$ Mendelian disorder
$(C)$ Allosomal Monosomy	$(iii)$ Klinefelter's Syndrome
$(D)$ Cystic fibrosis	$(iv)$ Down's Syndrome