Balance the equation and identify the type of reaction for ? p4(s) + ? ca(s) → ? ca3p2(s). 1. 2; 6; 2 — decomposition 2. 2; 6; 2 — displacement 3. 1; 6; 2 — displacement 4. 1; 6; 2 — synthesis 5. 2; 6; 2 — synthesis 6. 1; 6; 2 — decomposition

4. 1; 6; 2 — synthesis

Explanation:

Decomposition reaction is defined as the reaction in which a single large substance breaks down into two or more smaller substances.

Single displacement reaction is defined as the reaction in which more reactive element displaces a less reactive element from its chemical reaction.

The reactivity of metal is determined by a series known as reactivity series. The metals lying above in the series are more reactive than the metals which lie below in the series.

Synthesis reaction is defined as the reaction in which smaller substances combine in their elemental state to form a larger substance.

The unbalanced combustion reaction is shown below as:-

On the left hand side,  

There are 4 phosphorus atoms and 1 calcium atom

On the right hand side,  

There are 2 phosphorus atoms and 3 calcium atoms

Thus,  

Right side, must be multiplied by 2 to balance phosphorus.

Left side, is multiplied by 6 so to balance the whole reaction.

Thus, the balanced reaction is:-

Thus, - 4. 1; 6; 2 — synthesis

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."