Answer:
option A is correct ( sodium, calcium and barium)
Explanation:
Given compounds:
Sodium chloride , calcium sulfide, barium oxide
We know that metals form positive ions. In order to solve the problem we must identify the metals from given compounds.
Na⁺Cl⁻
Ca²⁺S²⁻
Ba²⁺O²⁻
We can see that sodium, calcium and barium contain positive charges.
Thus option A is correct.
Because sodium have one valance electron. When it combine with chlorine sodium lose its one electron to complete the octet and chlorine accept it to complete its octet. Thus sodium form positive ion and chlorine form negative ion.
Similarly barium and calcium are present in group 2. Both have two valance electron. When they lose them cation are formed.
Other option are incorrect because,
Option B have sulfur and oxygen which are anion.
Option C have chlorine which is also anion
Option D have chlorine, sulfur and oxygen that are anions.
The answer would be C. In fact, letter A already defines the Law of Definite Proportions. On the other hand, J.J. Thomson was responsible for the discovery of electrons through cathode ray tube experiments. The rest of the choices are true.
Yellow because Pangea all the continents were together
Answer: Energy of reactants = 30, Energy of products = 10
Exothermic
Activation energy for forward reaction is 10.
Explanation:
Exothermic reactions are defined as the reactions in which energy of the product is lesser than the energy of the reactants. The total energy is released in the form of heat and 
for the reaction comes out to be negative.
Energy of reactants = 30
Energy of products = 10
Thus as energy of the product < energy of the reactant, the reaction is exothermic.
Activation energy 
is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.
for forward reaction is (40-30) = 10.
Answer:
Many areas of the United States experience explosive population growth. <u>The more people that reside someplace, the more demand there is for water there.</u> Often these urban-growth <u>expansions are unplanned and place extraordinary stress on the water supply system, mainly on the groundwater.</u> <u>The stress often depletes groundwater supply, thereby causing wells to dry up.</u> Then water must be brought from somewhere else to support the local population.
Such situations have occurred all over the United States. For example, increased population growth in the southwestern United States has significantly lowered the water table 50 to 200 feet (depending on the area) since the 1940s. Managing urban growth, efforts to reduce water demand, conservation of the resource, and attempts to increase the water supply all address the problem of exceeding water resource limits.
<u>Human activities affect groundwater quality.</u>
<u>Here are some sources </u>and possible solutions to groundwater pollution:
<u>Agriculture</u>—Reduce usage of pesticides and fertilizers.
<u>Landfills</u>—Monitor for leakage and repair linings.
<u>Underground storage tanks</u>—Remove damaged and unused tanks.
<u>Household wastes</u>—Properly dispose of household hazardous waste.
<u>Septic tank leaks</u>—Properly maintain and repair tanks.
Explanation:
This came from the K12 learning course read this and the answer will be there. I underlined the important parts for the answer.
