Number one a and b are automatically out if you decrease the pitch or frequency you wont hear it louder it does not add up ok?
number 2 the answer would be C the higher the frequency the higher the pitch the lower the frequency the lower the pitch this just comes back to common sense. for example you cant decrease the frequency and than expect a louder pitch its like saying I am going to smash the key on this piano with all my strength and it will make a small very low pitch sound you get what I mean so your answer would indeed be C.
C that is the condensation point
Answer:
A production certificate Shows that the aircraft met FAA construction and performance standards
Explanation:
Federal Airport Authority (FAA), is the body that check the standard operations of air craft activities in a country.
Answer:
Input impedance of this transformer is 50 ohms.
Explanation:
Given that,
Number of turns in the primary coil, 
Number of turns in the secondary coil, 
Output impedance of the transformer, 
The number of turns and the impedance ratio in the step down transformer is given by :

So, the input impedance of this transformer is 50 ohms. Hence, this is the required solution.