Maria and Jane set up a lemonade stand one summer to earn money for a trip to the beach. They noticed that the hotter the day, the more glasses of lemonade they sold. They mixed up the lemonade exactly the same way every day: the same amount of sugar, lemon juice, and water. They added ice to the glass when they poured the drink. They always used the same size glass. They decided to chart their sales in order to figure out how much lemonade to make each day, using the weather forecast as their guide. Identify the independent, dependent, and controlled variables in the girls' experimental data.

Glass size
Water used
Daily temperature
Amount of sugar
Amount of lemon juice
Numbers of glasses sold
Timing adding ice

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.  

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.

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.