Answer: 
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
Here iron is having an oxidation state of +3 called as 
cation and oxide 
is an anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral 
.
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
Answer:
42.0g/mol
Explanation:
The steps for this question is to use the ideal gas law, and then use n=m/M to find molar mass.
PV = nRT
n= PV/RT
Change 23 degrees to 296.15 K and 684mmHg to kpa
n = (91.1925kpa)(2.00L)/(8.314Lkpa/mol K)(296.15K)
n= 0.074mol
n = m/M
M = m/n
M = 41.98489g/mol
Answer:
B. The air pressure would increase 2X
Explanation:
Pressure = density × acceleration due to gravity × height
p = ρ × g × h
Pressure is force per unit area
p = F/a
Density is mass per unit volume
Pressure is directly proportional to density hence, any change in the density of a body directly affects the change in pressure of the body and vice versa.
Answer:
D. 
Explanation:
Your unbalanced nuclear equation is
It is convenient to replace the question mark by an atomic symbol, 
, where <em>x</em> = the atomic number, <em>y</em> = the mass number, and <em>Z</em> = the symbol of the element .
Then your equation becomes
The main point to remember in balancing nuclear equations is that the sums of the superscripts and the subscripts must be the same on each side of the equation.
Then
55 = <em>x</em> - 1, so <em>x</em> = 55 + 1 = 56
135 = <em>y</em> + 0, so <em>y</em> = 135
Element 56 is barium, so the nuclear equation becomes
