Marie Curie discovered polonium and radium. Hope this helps:))) Please, mark Brainliest!
respiratory and lymphatic
Answer: (Chlorine-35)
Element X is Ca
Explanation:
Number of proton plus the number of electron gives the mass number.
The formula mass of a molecule is the sum of the atomic weights of the atoms in the empirical formula of the compound. It is also known as Formula Weight.
The atomic weights of
N = 14.01 amu
H = 1.00 amu
P = 30.97 amu
O = 16.0 amu
Now, we will calculate now the formula mass of a given substance
3(14.01) + 12(1.00) + 1(30.97) + 4(16.0) = 42.03 + 12.00 + 30.97 + 64.0 = 149.0 amu
Therefore, the formula mass for (NH4)3PO4 is 149.0 amu
Answer : The correct answer for change in freezing point = 1.69 ° C
Freezing point depression :
It is defined as depression in freezing point of solvent when volatile or non volatile solute is added .
SO when any solute is added freezing point of solution is less than freezing point of pure solvent . This depression in freezing point is directly proportional to molal concentration of solute .
It can be expressed as :
ΔTf = Freezing point of pure solvent - freezing point of solution = i* kf * m
Where : ΔTf = change in freezing point (°C)
i = Von't Hoff factor
kf =molal freezing point depression constant of solvent.
m = molality of solute (m or
)
Given : kf = 1.86 
m = 0.907
)
Von't Hoff factor for non volatile solute is always = 1 .Since the sugar is non volatile solute , so i = 1
Plugging value in expression :
ΔTf = 1* 1.86
* 0.907
)
ΔTf = 1.69 ° C
Hence change in freezing point = 1.69 °C