Which of the following reactions are exothermic?

 

$$\begin{gathered} 1) C + O2 → CO2 \\ 2) 2Mg + O2 → 2MgO \\ 3) CuSO4 + 5H2O → CuSO4.5H2O \\ 4) All the above \end{gathered}$$

Forms taken up by plants: Mg++ Functions in plants: a part of the chlorophyll molecule -essential in photosynthesis: related to phosphorus metabolism: large quantities found in seed.Mg deficiency symptoms: Mg is mobile, so symptoms occur first in old leaves; A whitish or yellowish striping effect on grasses.

Carbon dioxide (CO2) gas dissolved in water can cause water to become acidic.The acidity of water from dissolved CO2 can be reduced by a base such as baking soda (sodium bicarbonate).

When exposed to certain frequencies of radiation, such as radio waves, the subatomic particles called electrons that orbit an atom's nucleus will "jump" back and forth between energy states. Clocks based on this jumping within atoms can therefore provide an extremely precise way to count seconds.It is no surprise then that the international standard for the length of one second is based on atoms. Since 1967, the official definition of a second is 9,192,631,770 cycles of the radiation that gets an atom of the element called caesium to vibrate between two energy states.

Histones are highly alkaline proteins found in eukaryotic cell nucleusthat package and order the DNA into structural units called nucleosomes. They are the chief protein components of chromatin, acting as spools around which DNA winds, and playrole in gene regulation.