Answer:
700 calories
Explanation:
Using the formula below:
Q = m × c × ∆T
Where;
Q = amount of heat required (calories)
m = mass of substance (g)
c = specific heat of substance (cal/g°C)
∆T = change in temperature (°C)
According to this question, the following information was provided;
Q = ?
m = 20g
c = 1.0 cal/g °C
∆T = 40°C - 5°C = 35°C
Using the formula; Q = m × c × ∆T
Q = 20 × 1 × 35
Q = 700 calories
Hence, 700 cal of heat energy is needed to raise 20 g of H2O from 5°C to 40°C.
<u>Given:</u>
Initial amount of carbon, A₀ = 16 g
Decay model = 16exp(-0.000121t)
t = 90769076 years
<u>To determine:</u>
the amount of C-14 after 90769076 years
<u>Explanation:</u>
The radioactive decay model can be expressed as:
A = A₀exp(-kt)
where A = concentration of the radioactive species after time t
A₀ = initial concentration
k = decay constant
Based on the given data :
A = 16 * exp(-0.000121*90769076) = 16(0) = 0
Ans: Based on the decay model there will be no C-14 left after 90769076 years
Answer:
Strontium
Explanation:
In the periodic table, an element with two (2) valence electrons is found on group 2. Group 2 is a group of the periodic table that harbors element called ALKALINE EARTH METALS. As the name implies, they are metals that possess shiny and solid characteristics at room temperature.
Group 2 elements include the following: Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), barium (Ba), and radium (Ra). Based on the descriptive information in this question, the element being described is a GROUP 2 element. Based on the elements in the option, only STRONTIUM (Sr) is a group 2 element.
Answer:
r= 0.9949 (For 15,000)
r=0.995 (For 19,000)
Explanation:
We know that
Molecular weight of hexamethylene diamine = 116.21 g/mol
Molecular weight of adipic acid = 146.14 g/mol
Molecular weight of water = 18.016 g/mol
As we know that when adipic acid and hexamethylene diamine react then nylon 6, 6 comes out as the final product and release 2 molecule of water.
So
So
Mo= 226.32/2 =113.16 g/mol
Given that
Mn= 15,000 g/mol
So
15,000 = Xn x 113.16
Xn = 132.55
Now by using Carothers equation we know that
By calculating we get
r= 0.9949
For 19,000
19,000 = Xn x 113.16
Xn = 167.99
By calculating in same process given above we get
r=0.995
Look up chromium on periodic table.
It's atomic number is 24.
It gives number of protons in an element.
Since the atom is uncharged (no extra or subtracted electrons), the number of protons will equal the number of electrons.
