Which letter is silent.

Q1 - Which letter is silent?- Knife

k
f

Q2 - Which letter is silent?- Through

g
h
g + h

Q3 - Which letter is silent?- Plumber

m
b

Q4 - Which letter is silent?- Debt

b
t

Q5 - Which letter is silent?- Night

g
h
g + h

Q6 - Which letter is silent?- Doubt

b
t
b + t

Q7 - Which letter is silent?- Chemistry

c
h

Q8 - Which letter is silent?- Parliament

i
the second a

Q9 - Which letter is silent?- Acquaintance

c
q

Q10 - Which letter is silent?- Psychology

p
s

Q11 - Which letter is silent? - Marriage

i
a

Q12 - Which letter is silent? - Thumb

h
m
b

Q13 - Which letter is silent? - Knee

k
n