At stp (standard temperature and pressure), the temperature is T=0 C=273 K and the pressure is p=1.00 atm. So we can use the ideal gas law to find the number of moles of helium:

where p is the pressure (1.00 atm), V the volume (20.0 L), n the number of moles, T the temperature (273 K) and

the gas constant. Using the numbers and re-arranging the formula, we can calculate n:
It would be negative regardless of what you define as a positive direction.
Answer:
Wavelength of the sound wave that reaches your ear is 1.15 m
Explanation:
The speed of the wave in string is

where T= 200 N is tension in the string ,
=1.0 g/m is the linear mass density


Wavelength of the wave in the string is

The frequency is

The required wavelength pf the sound wave that reaches the ear is( take velocity of air v=344 m/s)

Answer:
Explanation:
Frequency refers to the number of occurrences of a periodic event per time and is measured in cycles/second. In this case, there is 1 cycle per 2 seconds. So the frequency is 1 cycles/2 s = 0.5 Hz.