We have to round off each measurement to the number of significant figures.
The correct answers are: 265.9, 0.00045 and 65 respectively.
265.991 when expressed in 4 significant figure it rounds off as 265.9 because 265.9 represents the value 265.991.
0.0004513 when expressed in 2 significant figure it rounds off as 0.00045 because zero before and after decimal are not significant.
6593 when expressed in 2 significant figure it rounds off as 65.
It’s a centrifuger there are many steps to this do I advise looking on the internet or i could explain if needed
Answer:
0.027 mole of NaOH.
Explanation:
We'll begin by obtaining the number of mole H2SeO4 in 45mL of 0.30M H2SeO4
This is illustrated below:
Molarity of H2SeO4 = 0.3M
Volume of solution = 45mL = 45/1000 = 0.045L
Mole of H2SeO4 =...?
Mole = Molarity x Volume
Mole of H2SeO4 = 0.3 x 0.045
Mole of H2SeO4 = 0.0135 mole
Next, the balanced equation for the reaction. This is given below:
H2SeO4 + 2NaOH –> Na2SeO4 + 2H2O
From the balanced equation above,
1 mole of H2SeO4 required 2 moles of NaOH.
Therefore, 0.0135 mole of H2SeO4 will require = 0.0135 x 2 = 0.027 mole of NaOH.
Therefore, 0.027 mole of NaOH is needed for the reaction.
The answer to your questions are
Question 1 - D - stationary
Question 2 - C - I'm not 100% sure
Question 3 - A - the northern subtropical jet stream
Question 4 - A - cold
Half life of a radio-active material is refereed to the time required for reducing its activity to 50 %.
Now, when I-131 passes 1st half life, it's activity will reduce to half i.e. 50%
When, I-131 passes 2nd half life, activity of I-131 will be reduced to 25%
On passing, 3rd half-life, percent activity of the I-131 <span>remaining will be 12.5 %.</span>
