Answer:
Elaina's scientific investigation is missing controlled variables.
Explanation:
A good scientific investigation should vary only the factor that is studied (the speed of the music. All other factors should be kept constant.
She hasn’t controlled for <em>volume</em>. The volume of the music may affect the rate at which the listener’s heart rate will increase. She should have measured each person’s pulse after the same period of listening.
She hasn’t controlled for <em>age</em>. A grandmother may respond to loud music differently from a teenager. All her subjects should be about the same age.
She hasn’t controlled for <em>wakefulness</em>. A person may respond to music differently when awake than when asleep.
Answer : Option 'D' is correct.
= 
Explanation 1) : 1 m = 100 cm
or 
= 
= = 
Explanation 2) : 1 m = 1000 mm
= 
= =
Option 'D' is right.
<span>Displaced volume :
</span>Final volume - <span>Initial volume
</span>13.45 mL - 12.00 mL => 1.45 mL
Mass = 4.50 g
Therefore:
density = mass / volume
D = 4.50 / 1.45
<span>D = 3.103 g/mL </span>
Answer:
20 kJ/mol
Explanation:
From ∆G°= -RTlnK
But
Ag2SO4(s)<----------->2Ag+(aq) + SO4^2-(aq)
Ksp= [2Ag+]^2 [SO4^2-]
But Ag+ = 0.032M
Ksp= (2×0.032)^2 (0.032)
Ksp= 1.31072×10^-4
∆G°= -RTlnK
∆G°= -(8.314× 298×(-8.93976))= 20KJmol-1( to the nearest KJ)
Answer:- Mass of copper piece is 290 gram.
Solution:- We know that, mass = density * volume
density of copper is given as 8.96 gram per mL.
Volume of copper piece is the rise change in volume.
Volume of copper piece = 137 mL - 105 mL = 32 mL
Let's multiply the volume by density to calculate the mass of copper:
mass of copper = 
mass of copper = 286.72 g
Volume has two significant figures, so if we round the mass to two significant figures then it becomes 290 g.
