I think its b too but i may be wrong
1. Frequency: 
The energy given is the energy per mole of particles:
1 mole contains a number of Avogadro of particles, 
, equal to
particles
So, by setting the following proportion, we can calculate the energy of a single photon:
This is the energy of a single photon; now we can calculate its frequency by using the formula:
where
is the Planck's constant
f is the photon frequency
Solving for f, we find
2. Wavelength: 
The wavelength of the photon is given by the equation:
where
is the speed of the photon (the speed of light). Substituting,
Answer:We are usually not aware of the electric force acting between two everyday objects because most everyday objects have as many plus charges as minus charges. Option A
Explanation:An electric force is exerted between any two charged objects( either positive or negative). Objects with the same charge will repel each other, and objects with opposite charge will attract each other. The strength of the electric force between any two charged objects depends on the amount of charge that each object contains and on the distance between the two charges. Electric charges are generated all around us due to different surfaces bearing different types of charges. We are usually not aware of it because the quantity of positive charges equals the number of negative charges.
The answer is D. As the ambulance gets closer, the sound waves are compressed relative to the person; so the frequency increases.
Answer:
It is called a surface wave (rayleigh wave) that transmits its energy with the wind blowing onto its surface.Hope this helps
