The correct options are as follows:
1. A.
A synthesis reaction is a type of reaction in which two or more reactants combine together to form only one product. Synthesis reaction always release energy in form of light and heat, therefore, they are usually exothermic reactions. In the option given in A, nitrogen and nitrogen combine together to form ammonia; this is a synthesis reaction.
2. D
A radioactive half life refers to the amount of time it will take for half of an original radioactive isotope to decay.
In the question given above, the half life of the element is 1000. Thus, in 1000 years only half of the original amount will remain. In another 1000 years only 1/4 of the original amount will remain and in another 1000 years only 1/8 of the original amount will remain. Therefore, it will take 3 half lives before 1/8 of the original sample remain.<span />
In the case of an emergency where you might not have enough time to read several lines of writing, not to mention trying to find the hazard warnings when the whole bottle is probably covered in writing, it is much easier to locate and read universal hazard symbols.
a pure compound because an element is untouched and is just itself
The equation : y=3x-5
<h3>Further explanation
</h3>
Straight-line equations are mathematical equations that are described in the plane of cartesian coordinates
General formula
y-y1 = m(x-x1)
or
y = mx + c
Where
m = straight-line gradient which is the slope of the line
x1, y1 = the Cartesian coordinate that is crossed by the line
c = constant
The formula for a gradient (m) between 2 points in a line
m = Δy / Δx
