The dichloromethane (DCM) has less density than water and also the polarity of water is much more than DCM. So the mixture of water and dichloromethane will always be a heterogeneous mixture. In the mixture dichloromethane will be always up of the water layer. The volume of the separatory funnel which contains the mixture of DCM and water must have to be more than the total volume of the liquids thus the volume of the funnel will be more than (50+50) = 100mL.
The caution have to consider during the separation are-
1. The separatory funnel have to shake well with lid and have to settle down for some times until the two liquid separated.
2. The lid should be open very slowly as the vapor pressure of DCM is more and it will float on the water.
3. After this the stopcock should be opened and slowly the water will come out first followed by DCM.
Answer:
the oxidation state od boron in sodium boron hydride is (+3).
Reaction:

Magnesium is a stronger reducing agent than copper and is thus able to reduce copper(II) oxide.
Products of the reaction: Magnesium oxide and metallic copper.
No, this item is not made of pure silver because if it has been made from pure silver that it would have displaced only 1.16cm³ of water but due to the addition of some other low-density element it displaces 1.9cm³ of water.
<u>For pure silver</u>
density of pure silver is = 10.49 g/cm³
mass of silver = 12.2 gram
since, density = mass/volume
volume = mass/density
= 12.2/10.49 cm³
= 1.16 cm³
But the actual displaced water is <u>1.9cm³</u>, which means some other element of lower density has been added.
Therefore, it is clear that the given jewelry is not made of pure silver.
Learn more about silver here:-brainly.com/question/17086277
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Number of atoms = mole x Avogadro’s Number
= 0.1 x 6.022 x 10^23
= 6.022 x 10^22