A(n) _______________ compound is a group of atoms held together by chemical bonds.

Mendeleev saw the properties of the elements repeated in an orderly way when he organized them according to increasing atomic mass. Mendeleev was als the first one who successfully arranged the elements in the periodic table and this is what we have been using today.

Answer: Density

Explanation:

The correct answer is conduction

There are a number of ways to express concentration of a solution. This includes molarity. Molarity is expressed as the number of moles of solute per volume of the solution. The mass of NaOH needed for the solution is calculated as follows:

2 M = amount in moles of solute / 2.5 L

amount in moles of solute = 5 mol NaOH

amount in grams = 5 x 40 = 200 grams NaOH

Answer:

                 Mass = 200 g

Solution:

             Molarity is the amount of solute dissolved per unit volume of solution. It is expressed as,

                         Molarity  =  Moles / Volume of Solution    ----- (1)

Data Given;

                  Molarity  =  2.0 mol.L⁻¹

                  Volume  =  2.5 L

                   M.Mass  =  40.0 g.mol⁻¹

First calculate Moles as,

                        Moles  =  Molarity × Volume

Putting Values,

                        Moles  =  2.0 mol.L⁻¹ × 2.5 L

                         Moles  = 5 mol

Secondly, calculate Mass using following formula,

                        Moles  =  Mass ÷ M.Mass

Solving for Mass,

                        Mass  =  Moles × M.Mass

Putting Values,

                        Mass  =  5 mol × 40.0 g.mol⁻¹

                         Mass =  200 g

Solution Preparation:

                                    Add 200 g of NaOH in a Volumetric Flask and add distilled water upto the mark of 2.5 L. Shake it and you have prepared a 2.5 L of 2.0 M solution of NaOH.