Answer:
For the formation of nitrogen dioxide, the reactants used are nitrogen monoxide and oxygen gas. 2 moles of nitrogen monoxide gas react with 1 mole of oxygen gas to produce 2 moles of nitrogen dioxide gas.
Explanation:
Octet rule states that an atom or element in the periodic table tends to combine with other atoms or elements and tries to attain 8 electrons in the outermost shell like the noble gas to attain stability.
1. So those elements which can easily attain octet rule are highly active.
eg: Sodium and chlorine.
Sodium has one outermost electron and can attain octet rule by losing this one electron
Chlorine has 7 outhermost electron and can attain octet rule by gaining one electron.
So Sodium and Chlorine are highly active as they can easily attain stability by losing or gaining one electron to attain octet.
2. And thus octet rule easily explains why an element or atom is highly active.
D.because the water is needed to wet the sand and keep the reaction safe
The radioactive decay obeys first order kinetics
the rate law expression for radioactive decay is
Where
A0 = initial concentration
At = concentration after time "t"
t = time
k = rate constant
For first order reaction the relation between rate constant and half life is:
Let us calculate k
k = 0.693 / 72 = 0.009625 years⁻¹
Given
At = 0.25 A0
time = 144 years
So after 144 years the sample contains 25% parent isotope and 75% daughter isotopes**
Simply two half lives