The answer is; 2.
To balance a chemical equation, the moles on one side of the equation has to be the same as that on the other side. This ensures that the law of conservation is observed because matter or energy can't be created or destroyed but can only be transformed from one form to another.
In this equation, putting 2 in front of NaCl ensures that there are 2 moles of Na and CL just as there are 2 moles of Na and CL in the reactants side.
Answer:
<em>a) 28877 AU</em>
<em>b) 1.795 sec</em>
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Explanation:
Time it took the radio signal to reach earth = 4 hours = 4 x 3600 = 14400 s
speed of radio signal = speed of vacuum speed of light = 3 x 10^8 m/s
Distance traveled by this signal = speed x time
distance = 3 x 10^8 x 14400 = 4.32 x 10^12 m
One Astronomic unit AU is the distance between the Earth and the sun and it is approximately equal to 1.496 x 10^8 m
The distance traveled by the signal in AU = (4.32 x 10^12)/(1.496 x 10^8) = <em>28877 AU</em>
b) The minimum separation between Earth and Mars = 0.36 AU
This distance = 0.36 x 1.496 x 10^8 = 538560000 m
Time that will be taken for a radio signal to travel this distance = distance/speed
==> 538560000/(3 x 10^8) = <em>1.795 sec</em>
