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.
Answer:
When the hammer is in the sun, heat flows by radiation
When you pick up the hammer, heat flows by conduction
Explanation:
As the hammer lies in the sun, heat is transferred to the hammer by radiation. Heat energy reaches the earth from the sun by radiation. Radiation is a mode of beat transfer in which heat is transferred without a material medium.
When you pick up the hammer, heat flows to your hand by conduction because your body is a conductor of heat.
