Pls answer all questions

5:-c
The 3multiples are 25,50,75
6:-c
[tex]\\ \sf\longmapsto 6\:of\:2+9-5[/tex]
[tex]\\ \sf\longmapsto 6(11-5)[/tex]
[tex]\\ \sf\longmapsto 6(6)[/tex]
[tex]\\ \sf\longmapsto 36[/tex]
7:-a
12,17
8:-c
HCF=2×2×11=44
9:-c
LCM of 9 and 5 is 45 hence its true
10:-c
HCF of two consecutive numbers is 1