Can someone explain #3

This is a unit conversion problem. Nm (nanometer) is smaller than mm (millimeter).

1 mm = 1/10³m = 1 x 10⁻³ m

1 nm = 1/10⁹ m = 1 x10⁻⁹ m

1 m = 1 x 10⁹ nm

Hence, 2 mm = 2 x 10⁻³ m

Then we can convert 2 x 10⁻³ m to nm by multiplying with 10⁹.

Then 2 mm = 2 x 10⁻³ m = 2 x 10⁻³ x 10⁹ nm = 2 x 10⁶ nm.

Hence, the thickness of nickel is 2 x 10⁶ nm.

Answer : The procedure to separate the mixture of sugar, black pepper and pebbles would require physical methods.

First step is to pass the mixture through a grid that traps the pebbles in it and allows the passage of black pepper and sugar from it or alternatively, physically hand-picking up the pebbles can also be done.

Next step is to add water to the mixture to the sugar and black pepper, stir this solution until all the sugar dissolves in the water. Then pass this solution from a filter paper and collect the filtrate in a beaker.

The residue would contain the black pepper on it, it can be dried after separation.

To obtain the sugar which is dissolved in water, one can evaporate the water in it and get the sugar at the bottom of the beaker.

Explanation:

A precipitate is an insoluble solid that does not dissolve in a chemical reaction or or mixture.

For example,

Therefore, the precipitate formed can be separated out by filtration method.

As this method will most suitably extract the precipitate and separate it from the remaining solution.