Answer:
0.2598 M
Explanation:
Molarity is mol/L, so we have to convert the grams to moles and the mL to L. To convert between grams and moles you need the molar mass of the compound, which is 36.46g/mol.
Round to the lowest number of significant figures = 0.2598 M
The number of neon moles that occupy a volume of 14.3 l at STP is calculated as follows
At STP 1 mole = 22.4 liters
what about 14.3 liters
by cross multiplication
= (1 mole x 14.3 l)/22.4 l =0.638 moles of neon
The much of the sample that would remain unchanged after 140 seconds is 2.813 g
Explanation
Half life is time taken for the quantity to reduce to half its original value.
if the half life for Scandium is 35 sec, then the number of half life in 140 seconds
=140 sec/ 35 s = 4 half life
Therefore 45 g after first half life = 45 x1/2 =22.5 g
22.5 g after second half life = 22.5 x 1/2 =11.25 g
11.25 g after third half life = 11.25 x 1/2 = 5.625 g
5.625 after fourth half life = 5.625 x 1/2 = 2.813
therefore 2.813 g of Scandium 47 remains unchanged.
