Answer:
A) -270 kJ; B) +15 kJ; C) + 70 kJ
Step-by-step explanation:
ΔE = q + w
By convention, anything leaving the system is negative and anything entering the system is positive.
A) ΔE = -220 kJ - 50 kJ = -270 kJ
B) ΔE = +65 kJ - 50 kJ = +15 kJ
C) ΔE = -50 kJ + 120 kJ = +70 kJ
0.05m x 0.05m x L x 7300 kg/m^3 = 4.578 kg L = 0.251 m = 25.1 cm
The average atomic mass of the mystery element : 1637.88 amu
<h3>Further explanation
</h3>
The elements in nature have several types of isotopes
Isotopes are elements that have the same Atomic Number (Proton)
Atomic mass is the average atomic mass of all its isotopes
In determining the mass of an atom, as a standard is the mass of 1 carbon-12 atom whose mass is 12 amu
An atomic mass unit = amu is a relative atomic mass of 1/12 the mass of an atom of carbon-12.
The 'amu' unit has now been replaced with a unit of 'u' only
Mass atom X = mass isotope 1 . % + mass isotope 2.%
..
Isotope #1 - 85 particles, Isotope #2 - 90 particles, Isotope #3 - 45 particles, so total particles :
% particles :
The average atomic mass of the mystery element
Answer:
Option 4 is correct (72 seconds)
Explanation:
Option 4 is correct (72 seconds)
The formula we are going to use is:
Where:
A is the final concentration
A_o is the initial concentration
k is the constant
t is the time
Half-Life=0.693/k
Half-life in our case=24 seconds
k=0.693/24
k=0.028875 s^-1
Since the concentration is decreased by 87.5 % which means only 12.5%(100-87.5%) is left.
The ratio will become 0.125
t≅ 72 seconds