Answer:
The wavelength of the radio wave is 3.003 m.
The energy of the radio wave is
.
Explanation:
Frequency of the radio waves, ν = 99.9 MHz = 
Wavelength and frequency are related to each other by realtion:

= Wavelength of the wave
c = speed of the light
ν = Frequency of the wave

The wavelength of the radio wave is 3.003 m.
The energy of the electromagnetic wave is given by Planck's equation:

h = Planck's constant = 
The energy of the radio wave with 99.9 MHz frequency will be:


The energy of the radio wave is
.
Answer:We will use an acid to test whether sample contains calcium carbonate or not.
Explanation:
Calcium carbonate reacts with acids to give off carbon-dioxide gas ,water and calcium chloride. it is a salt of strong base calcium hydroxide and weak acid carbonic acid.

Evolution of carbon-dioxide on the reaction is also termed as effervescence.
If the sample contains the calcium carbonate strong effervesces will be observed and if not no effervescence will be observed.
We will use an acid to test whether sample contains calcium carbonate or not.
Answer:
0.0300 moles of H₂
Explanation:
The original equation is PV = nRT. We need to change this to show moles (n).
n = 
It's important to convert your values to match the constant (r) in terms of units.
30.0 kPa = 0.296 atm
2500 mL = 2.50 L
27 °C = 300 K
Now, plug those values in to solve:
n =
- for the sake of keeping the problem clean, I didn't include the units but you should just to make sure everything cancels out :)
Finally, you are left with n = 0.0300 moles of H₂