<span>3.2 grams
The first thing to do is calculate how many half lives have expired. So take the time of 72 seconds and divide by the length of a half life which is 38 seconds. So
72 / 38 = 1.894736842
So we're over 1 half life, but not quite 2 half lives. So you'll have something less than 12/2 = 6 grams, but more than 12/4 = 3 grams.
The exact answer is done by dividing 12 by 2 raised to the power of 1.8947. So let's calculate 2^1.8947 power
= 12 g / (e ^ ln(2)*1.8947)
= 12 g / (e ^ 0.693147181 * 1.8947)
= 12 g / (e ^ 1.313305964)
= 12 g / 3.718446464
= 3.227154167 g
So rounded to 2 significant figures gives 3.2 grams.</span>
Answer: 757m/s
Explanation:
Given the following :
Mole of neon gas = 1.00 mol
Temperature = 465k
Mass = 0.0202kg
Using the ideal gas equation. For calculating the average kinetic energy molecule :
0.5(mv^2) = 3/2 nRt
Where ;
M = mass, V = volume. R = gas constant(8.31 jK-1 mol-1, t = temperature in Kelvin, n = number of moles
Plugging our values
0.5(0.0202 × v^2) = 3/2 (1 × 8.31 × 465)
0.0101 v^2 = 5796.225
v^2 = 5796.225 / 0.0101
v^2 = 573883.66
v = √573883.66
v = 757.55109m/s
v = 757m/s
Answer:
342 m/s
Explanation:
The velocity of sound in air is approximated as:
v ≈ 331.4 + 0.6 T
where v is the velocity in m/s and T is the temperature in Celsius.
At T = 18:
v ≈ 331.4 + 0.6 (18)
v ≈ 342.2
The velocity is approximately 342 m/s.
