A substance where almost all have the same atomic number of protons
Answer: <em>The </em><em>alkali metals</em><em> reactivity is generally higher than the alkaline earth metals. </em>
Explanation: <em>This makes the alkaline earth metals with their two valence electrons less reactive than alkali metals with their one valence electron.</em>
<u>Alkali metals is ns1 and alkaline earth metals is ns2</u>
Answer:
(1) -12 Kcal/mol
Explanation:
Our answer options for this question are:
(1) -12 Kcal/mol
(2) -13 Kcal/mol
(3) -15 Kcal/mol
(4) -16 Kcal/mol
With this in mind, we can start with the chemical reaction (Figure 1). In this reaction, <u>two bonds are broken</u>, a C-H and a Br-Br. Additionally, a C-Br and a H-Br are <u>formed</u>.
If we want to calculate the enthalpy value, we can use the equation:
<u>ΔH=ΔHbonds broken-ΔHbonds formed</u>
If we use the energy values reported, its possible to calculate the energy for each set of bonds:
<u>ΔHbonds broken</u>
<u />
C-H = 94.5 Kcal/mol
Br-Br = 51.5 Kcal/mol
Therefore:
105 Kcal/mol + 53.5 Kcal/mol = 146 Kcal/mol
<u>ΔHbonds formed</u>
C-Br = 70.5 Kcal/mol
H-Br = 87.5 Kcal/mol
Therefore:
70.5 Kcal/mol + 87.5 Kcal/mol = 158 Kcal/mol
<u>ΔH of reaction</u>
<u />
ΔH=ΔHbonds broken-ΔHbonds formed=(146-158) Kcal/mol = -12 Kcal/mol
I hope it helps!
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Answer:
The mass of gold in crown is 960.61 g.And the volume of gold is
.
Explanation:
Density is defined as mass of the substance present in unit volume of the substance.
Mass of gold in an alloy of crown= m
Mass of silver in an alloy of crown = M
Volume gold in an alloy of crown= v
Volume of silver in an alloy of crown = V
Density of gold = 
Density of silver = 
Volume of the crown = 

..(1)
Mass of eh crown = 1050 g
..(2)
Solving equation (1) and (2):
m = 960.61 g
M = 89.39 g
Volume of the gold = v = 
Volume of silver = V = 
The mass of gold in crown is 960.61 g.And the volume of gold is
.
2 and a half
250 x 2 =500
250/2=125
and 125 is a half of 250
so your answer is
2 and a half