Hess's law states that enthalpy change for a reaction is independent of path, allowing calculation of ΔH by summing known reactions.

To solve this, you have to break it down into the same "Select then Arrange" flow:

1. Selection ($C$): * We need 3 Physics books. Since P1 is mandatory, we only need to choose 2 more from the remaining 4. Calculation: $\binom{4}{2} = 6$.

   • We need 2 Math books from 4. Calculation: $\binom{4}{2} = 6$.

   • Total selection combinations: $6 \times 6 = 36$.

2. Arrangement ($P$): * We have 5 books (3 Physics, 2 Math).

   • The "Gap Method" is best for the constraint "Math books not together."

   • First, arrange the 3 Physics books: $3! = 6$ ways.

   • This creates 4 possible gaps ( _ P _ P _ P _ ).

   • We must place the 2 Math books into these 4 gaps: $^4P_2 = 12$ ways.

   • Total arrangements per selection: $6 \times 12 = 72$.

3. Final Calculation:

   • $36 \text{ (selections)} \times 72 \text{ (arrangements)} = 2592$.

Correct Answer: D (1200 or more)

p = E/c = hν/c = h/λ.

Bulk modulus $K = \rho \frac{dP}{d\rho}$ [cite: 494].

• The change in density $d\rho = \frac{\rho dP}{K}$
• With $dP = P$, the increase is $\frac{\rho P}{K}$[cite: 497].