<u>Answer:</u> The remaining sample of X is 6.9 grams.
<u>Explanation:</u>
All the radioactive reactions follow first order kinetics.
The equation used to calculate rate constant from given half life for first order kinetics:
We are given:
Putting values in above equation, we get:
The equation used to calculate time period follows:
where,
= initial mass of sample X = 78 g
N = remaining mass of sample X = ? g
t = time = 16.5 min
k = rate constant = 
Putting values in above equation, we get:
Hence, the remaining amount of sample X is 6.9 g
Answer:
B = 1058.4 N
Explanation:
Given that,
The volume of a metal block, V = 0.09 m³
The density of fluid, d = 1200 kg/m³
We need to find the buoyant force when it's Completely immersed in brine. The formula for the buoyant force is given by :
g is acceleration due to gravity
So, the required buoyant force is 1058.4 N.
Answer:
He calculated his average speed.
Explanation:
Waldo calculated an average of his speed in 2 hours rather than his speed whilst driving which means instead of doing 50/1 hour = 50 mph, he did 50/2hours which is how he got 25 mph. Hope this helps!
Answer: C. Nicolas Copernicus
Explanation:
Copernicus's model of the universe (heliocentric theory) was refuting the long life geocentric theory (the Earth as the center of the universe) proposed by <u>Ptolemy</u> and accepted by the Catholic Church.
In this sense, <u>Ptolemy's model of the universe placed the Earth in the center of the known universe</u>, where our planet remains stationary while the other planets, the Moon and the Sun describe complicated orbits around it.
As Ptolemy was a respected astronomer and geographer, this idea was accepted for a long time, until Copernicus arrived with the new model.
186282 miles. Hope it helps
