Answer:
a person who excels at a particular sport or other activity.
Explanation:
google
A cold air mass moves into an area of warm air
Answer:
adds; convection
Explanation:
because in order for ice to melt, you need to add heat energy. convection is when you make something hot rise and something cold melt.
Answer:
an object is a rest upon a table
<u>Answer:</u> The speed of the electron is 
<u>Explanation:</u>
To calculate the speed of electron for given wavelength, we use the equation given by De-Broglie's, which is:

where,
= De-Broglie's wavelength = 
h = Planck's constant = 
m = mass of the electron = 
v = speed of the electron = ?
Putting values in above equation, we get:

Hence, the speed of the electron is 