I think the correct answer would be the first option. It is the solid phosphorus (P4) that will be the softest among these crystals. P4 is held by covalent bonding or sharing of electrons between atoms while ZnS, CuCl and SiO2 are being held by ionic bonding. Covalent bonding involves the overlapping of orbitals while ionic bonding has separation of the charges. Although covalent bonding is a strong type of bond, ionic bonding is much stronger as compared to the former. Being stronger, the compounds mentioned above with this type of bonding would tend to be harder than phosphorus which has covalent bonding only.
Answer:
acid rain falls in areas that have air pollution
Answer:
Its pressure will be 0.54 atm at 100 K.
Explanation:
Gay-Lussac's law indicates that, as long as the volume of the container containing the gas is constant, as the temperature increases, the gas molecules move faster. Then the number of collisions with the walls increases, that is, the pressure increases. That is, the pressure of the gas is directly proportional to its temperature.
Gay-Lussac's law can be expressed mathematically as the quotient between pressure and temperature equal to a constant:

Studying two different states, an initial state 1 and a final state 2, it is satisfied:

In this case:
- P1= 1.75 atm
- T1= 50 °C= 323 K (being 0 C=273 K)
- P2= ?
- T2= 100 K
Replacing:

Solving:

P2= 0.54 atm
<u><em>Its pressure will be 0.54 atm at 100 K.</em></u>
Answer:
creating new water molecules and lowering the amount of free H+ in the system, thereby raising the overall pH.
Explanation: