121.75 is really really really really really the right answer... For real
Answer:
single replacement
Explanation:
Step 1: Data given
single replacement = A reaction in which one element replaces a similar element in a compound. For example, a metal replaces an other metal.
The general form of a single-replacement (also called single-displacement) reaction is:
A+BC→AC+B
Decomposition = a reaction in which a compound breaks down into two or more simpler substances. The general form of a decomposition reaction is:
AB→A+B
Synthesis = A reaction that occurs when one or more compounds combines to form a complex compound:
A + B → AB
Double replacement: a reaction in which the positive and negative ions of two ionic compounds exchange places to form two new compounds.
The general form of a double-replacement reaction is:
AB+CD→AD+BC
Combustion reaction = a reaction in which a substance reacts with oxygen gas, releasing energy in the form of light and heat. Combustion reactions must involve O2 as one reactant.
The reaction Zn + 2HCl → ZnCl2 + H2
⇒ Does not involve O2 = NOT a combustion reaction
⇒ The compounds do not form a complex compound = NOT a synthesis
⇒ A compound does not break down into smaller substances = NOT a decomposition
⇒ There is a replacement between Zn and H. This is a <u>single replacement</u>, not a double replacement reaction.
Answer: The standard free energy change for a reaction in an electrolytic cell is always positive.
Explanation:
Electrolytic cells use electric currents to drive a non-spontaneous reaction forward.
Relation of standard free energy change and emf of cell
where,
= standard free energy change
n= no of electrons gained or lost
F= faraday's constant
= standard emf
= standard emf = -ve , for non spontaneous reaction
Thus 
Thus standard free energy change for a reaction in an electrolytic cell is always positive.
And a water molecule, this is called a dehydration synthesis. when 2 molecule combine, a water molecule leave.
Answer:
Approximately 1.9 kilograms of this rock.
Explanation:
Relative atomic mass data from a modern periodic table:
To answer this question, start by finding the mass of Pb in each kilogram of this rock.
89% of the rock is 
. There will be 890 grams of in one kilogram of this rock.
Formula mass of :
.
How many moles of formula units in that 890 grams of ?
.
There's one mole of 
in each mole of . There are thus 
of in one kilogram of this rock.
What will be the mass of that of ?
.
In other words, the in 1 kilogram of this rock contains 
of lead .
How many kilograms of the rock will contain enough to provide 1.5 kilogram of ?
.
