<span>a. It melts at 1455oC I know this is correct I need One more</span>
Answer:
New cells arise from existing cells.
Explanation:
According to the cell theory, "all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells"(Lumen Learning).
Cells are the basic unit of life. Some organisms consists of only one cell while other organisms have many cells and are called multicellular organisms.
In multicellular organisms, new cells are formed by the division of preexisting cells.
Answer:
A
Explanation:
Sodium has 11 electrons and Magnesium has 12 electrons. Since here you need to consider atoms, they must have equal amount of protons as electrons to be considered neutral, and so an atom.
So simply 11+12 =23
95.6 cal
are needed.
Explanation:
Use the following equation:
q
=
m
c
Δ
T
,
where:
q
is heat energy,
m
is mass,
c
is specific heat capacity, and
Δ
T
is the change in temperature.
Δ
T
=
T
final
−
T
initial
Known
m
=
125 g
c
Pb
=
0.130
J
g
⋅
∘
C
T
initial
=
17.5
∘
C
T
final
=
42.1
∘
C
Δ
T
=
42.1
∘
C
−
17.5
∘
C
=
24.6
∘
C
Unknown
q
Solution
Plug the known values into the equation and solve.
q
=
(
125
g
)
×
(
0.130
J
g
⋅
∘
C
)
×
(
24.6
∘
C
)
=
400. J
(rounded to three significant figures)
Convert Joules to calories
1 J
=
0.2389 cal
to four significant figures.
400
.
J
×
0.2389
cal
1
J
=
95.6 cal
(rounded to three significant figures)
95.6 cal
are needed.
Explanation:
The problem basically wants you to find a way to convert between the number of atoms present in the sample and the number of moles they are equivalent to.
To convert between atoms and moles we use something called Avogadro's constant, which basically acts as the definition of a mole.
More specifically, in order to have one mole of an element you need
6.022 x 10^23 atoms of that element. You can thus use this number as a conversion factor to take you from atoms to moles or vice versa.
In your case, you will have
3.90 x 10^ 26 atoms Zn x 1 mole Zn ( Avogrado’s constant) / 6.022 x 10^23 atoms Zn
= 6.5 x 10^8 is the answer
