The 2nd one I think but I need some points
The answer is b. The sum of the individual gas pressure in the mixture
<u>Answer:</u> The equation is given below.
<u>Explanation:</u>
Single replacement reactions are the chemical reactions in which more reactive metal displaces a less reactive metal from its chemical reaction. General equation for these reactions is given by the equation:

Metal A is more reactive than metal B.
The reactivity of metals is judged with the help of reactivity series. In this series, the metals lying above are more reactive than the metals which lie below in the series.
For the reaction of solid lithium metal and nitric acid, the equation follows:

This is a type of single replacement reaction because Lithium (more reactive metal) is replacing Hydrogen (less reactive metal) from the chemical reaction.
Answer:
Option B is correct.
Explanation:
They live in less extreme environment than most archaebacteria.
Hoped this helped.
Answer:
Neither is affected
Explanation:
The reaction occurs as follows:
K₂Cr₂O₇ + Pb(NO₃)₂ → PbCr₂O₇ + 2K⁺ + 2NO₃⁻
That means per mole of reaction you will have two moles of both K⁺ and NO₃⁻.
But volume is also doubled, doing that concentration of spectator ions doesn't change.
Right answer: Neither is affected
I hope it helps!