It's A, t<span>The figure is a molecule and an element.</span>
<u>Answer:</u> The true statement is iron can reduce
to gold metal
<u>Explanation:</u>
Single displacement reaction is defined as the reaction in which more reactive element displaces a less reactive element from its chemical reaction.
The reactivity of metal is determined by a series known as reactivity series. The metals lying above in the series are more reactive than the metals which lie below in the series.

Metal A is more reactive than metal B.
We are given:
Iron can reduce copper, silver can reduce gold, sodium can reduce iron and copper can reduce silver metal.
The increasing order of reactivity thus follows:

where, sodium is most reactive and gold is least reactive
For the given options:
<u>Option 1:</u> Copper cannot easily reduce sodium ion to sodium metal because it is less reactive.

<u>Option 2:</u> Iron cant easily reduce gold ion to gold metal because it is more reactive.

<u>Option 3:</u> Silver cannot easily reduce iron ion to iron metal because it is less reactive.

Hence, the true statement is iron can reduce
to gold metal
Answer: All changes of state involve the transfer or energy
Explanation: i got my information from this site
https://www.esrl.noaa.gov/gmd/education/info_activities/pdfs/CTA_the_water_cycle.pdf
Answer:1.
Explanation: This reaction is catalyzes by pyruvate dehydrogenase. Pyruvate being the end product of glycolysis has many fates after glycolysis,one of which is to enter the TCA(Tricarboxylic acid cycle) cycle. It is first converted to actetate by the action of pyruvate dehydrogenase. This enzyme converts pyruvate to acetate releasing CO2 and NADH because this oxidative decarboxylation of pyruvate is coupled with reduction of NAD+ which can feed into the electron transport chain.