There are 7 valence electrons in the atom :)
Atom is the
most basic unit of matter. They are the general term used to describe pieces of
matter. But a different kind of atom makes up an element. A combination of atom of different elements
creates a molecule. For example, you have water; it has a chemical formula of
H2O. If you separate H from O, you have two atoms. Two atoms for hydrogen and
one atom for oxygen. However, they are of different elements. And when you
combine them to form H2O, you create a molecule.
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Answer : The molal freezing point depression constant of X is 
Explanation : Given,
Mass of urea (solute) = 5.90 g
Mass of X liquid (solvent) = 450.0 g
Molar mass of urea = 60 g/mole
Formula used :

where,
= change in freezing point
= freezing point of solution = 
= freezing point of liquid X= 
i = Van't Hoff factor = 1 (for non-electrolyte)
= molal freezing point depression constant of X = ?
m = molality
Now put all the given values in this formula, we get
![[0.4-(-0.5)]^oC=1\times k_f\times \frac{5.90g\times 1000}{60g/mol\times 450.0g}](https://tex.z-dn.net/?f=%5B0.4-%28-0.5%29%5D%5EoC%3D1%5Ctimes%20k_f%5Ctimes%20%5Cfrac%7B5.90g%5Ctimes%201000%7D%7B60g%2Fmol%5Ctimes%20450.0g%7D)

Therefore, the molal freezing point depression constant of X is 
Elements and compounds. This is because in solutions and mixtures the substances are not bonded to each other or pure, you can separate and purify substances in solutions and mixtures (via techniques such as distillation, filtering) but you cannot separate compounds as they are bonded together.
Answer:
The reaction is a double displacement reaction
Explanation:
Let us consider the reaction equation of the reaction between ammonium oxalate and lithium acetate.
(NH4)2C2O4(aq) +2 CH3COOLi(aq) -------> 2NH4CH3CO2(aq) + Li2C2O4(s)
This is a displacement reaction. A double displacement reaction is a type of reaction in which two reactants exchange their ions to form two new compounds. Double displacement reactions usually lead to the formation of a solid product which is also called a precipitate.
The general form of a Double displacement reaction is of the format:
AB + CD → AD + CB
Where A,B,C and D represents different ions respectively.
A double displacement reaction can also be referred to as salt metathesis reaction, double replacement reaction, exchange reaction, or a double decomposition reaction, although the latter term is more strictly used when one or more of the reactants does not dissolve in the solvent.