Question 1 (1 point)
(05.01 lc)
in what form does the sun's energy arrive on earth? (1 point)
1) conduction
2) convection
3) frequency
4) radiation

Radiation

Explanation:

Thermal energy (heat) can be transferred between objects as long as there is a temperature difference between them. However, there needs to be some kind of medium transferring it. There are basically three ways in which the energy is transferred:

1. Conduction - transfer via the direct contact  

2. Convection - transfer via the circular movement of fluids or air caused by hotter layers moving upward and colder downwards.

3. Radiation - transfer via the waves from the invisible spectrum of electromagnetic radiation ( ultra-violet, infra-red...)

Frequency is not a type of energy transfer, but a number of times something is occurring in one second. When we say that the frequency is 200Hz it means that something is happening at a rate of 200 times in a second. It's most often used in describing oscillations.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-