Explanation:
Yes, a chemical reaction can happen with only one substance.
A typical example of such reaction is the radioactive decay.
Radioactive decay is the loss of elementary particles from an unstable nucleus, ultimately changing the unstable element into another more stable element. .
When radioactive elements are let alone, they decompose to form stable harmless elements.
An example of radioactive decay is attached in the image below;
Answer: Originally viewed as a single event, the Taconic orogeny is now known to consist of at least three episodes. The first took place in the Early Ordovician Epoch near Maine and Newfoundland. The second was centred on eastern Tennessee in the Middle Ordovician Epoch.
Answer:
He was an American statesman, politician, legal scholar. military commander, lawyer, banker and economist.
Pb + Mg(NO₃)₂ → Pb(NO₃)₂ + Mg
This reaction would NOT occur because Pb is less reactive than Mg and as such Pb cannot displace the Mg in order for the reaction to occur under normal conditions.
Mg + Fe(NO₃)₂ → Fe + Mg(NO₃)₂
This reaction would occur. This is because Mg is more reactive than Fe and as such can displace it in the reaction, thus allowing the reaction to occur under normal conditions.
Cu + Mg(NO₃)₂ → Cu(NO₃)₂ + Mg
This reaction would NOT occur. Mg is more reactive than Cu, and as such copper cannot displace magnesium in order for the reaction to occur under normal conditions.
Answer:
Explanation:
(a) Balanced reaction of gallium with oxygen is as follows:

(b) 
Multiply the carbon dioxide by 6 to balance carbon as follows:

After that multiply H2O by 7 to balance hydrogen as follows:

Finally balance oxygen by multiplying O2 by 19/2. Therefore, balanced reaction is as follows:

(c) 
first balance calcium, by multiply
by 3 as follows:

After that balance phosphorous by multiplying
by 2 as follows:

Finally balance Na by multiplying NaCl by 6. Therefore, balance reaction is as follows:
