Changes in pressure have a measurable effect: (select all that apply) Select all that apply:

in any system only in systems in which gases are involved
when there are equal numbers of moles of gas on the reactant and product sides of the equilibrium only
when the chemical reaction produces a change in the total number of gas molecules in the system

1. only in systems in which gases are involved

2. only when the chemical reaction produces a change in the total number of gas molecules in the system

Explanation:

According to Le Chatelier's principle, pressure will only affect a system in equilibrium containing gaseous reactants and products. However, change in the pressure will only affect the gaseous system in which the total number of moles of the reactants are different from the total number of moles of the products.

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.