Answer:
230
Th
90
Explanation:
The left side shows the element uranium with mass number 234 (superscript to the left of ths symbol) and atomic mass 92 (subscript to the left of the symbol).
So, you have to find the mass number and atomic numbers missing on the right side which added to those shown for the helium atom reach 234 and 92.
This the the mathematics:
1) Mass number of U - mass number of He = 234 - 4 = 230 ⇒ the mass number of the missing element is 230.
2) atomic number of U - atomic number of He = 92 - 2 = 90 ⇒ the atomic number of the missing element is 90.
Now, you use the atomic mass to identify the element. You do it by simply searching in a periodic table. There you find that the atomic number 90 corresponds to thorium, whose symbol is Th.
Now you have that the product that completes the right side of the decay equation is:
230
Th
90
U need to do it in cronological order
Answer:
The molarity (M) of the following solutions are :
A. M = 0.88 M
B. M = 0.76 M
Explanation:
A. Molarity (M) of 19.2 g of Al(OH)3 dissolved in water to make 280 mL of solution.
Molar mass of Al(OH)3 = Mass of Al + 3(mass of O + mass of H)
= 27 + 3(16 + 1)
= 27 + 3(17) = 27 + 51
= 78 g/mole
= 78 g/mole
Given mass= 19.2 g/mole
Moles = 0.246
Volume = 280 mL = 0.280 L
Molarity = 0.879 M
Molarity = 0.88 M
B .The molarity (M) of a 2.6 L solution made with 235.9 g of KBr
Molar mass of KBr = 119 g/mole
Given mass = 235.9 g
Moles = 1.98
Volume = 2.6 L
Molarity = 0.762 M
Molarity = 0.76 M
When the guard cell is filled with water and it becomes turgid, the outer wall balloons outward, drawing the inner wall with it and causing the stomate to enlarge.
I understand here "bias" to be the uncertainty of measurements. So the order will be the following:
6.4 ± 0.5 s
<span>6.6 ± 0.1 s,
</span><span>6.63 ± 0.01 s,
</span><span>6.52 ± 0.05 s,
</span>
(notice how the second number, the one behind the symbol ± gets smaller, as the bias gets smaller).
