Answer:
The answer is: (a) positive; (b) negative.
Explanation:
The change in enthalpy (ΔH) of a reaction is the amount of energy absorbed or released during a chemical reaction carried out at constant pressure.
a) In an endothermic chemical reaction, heat energy is absorbed by the system from the surrounding. Therefore, the sign of enthalpy change for an endothermic process is positive, ΔH= positive.
b) In an exothermic chemical reaction, heat energy is released by the system into the surrounding. Therefore, the sign of enthalpy change for an exothermic process is negative, ΔH= negative.
Explanation:
Deliquescent substances are solids that absorb moisture from the atmosphere until they dissolve in the absorbed water and form solutions. Efflorescent: Efflorescent substances are solids that can undergo spontaneous loss of water from hydrated salts.
The atoms combine to form compounds to attain stability in nature. The combination of atoms takes place by sharing of electrons between the atoms or complete transfer of electrons from one atom to another. Generally, atoms combine to complete their octet, that is to possess eight electrons in their outer most shell (noble gas configurations) except hydrogen which can attain stability by two electrons in its outer most shell.
Since germanium has 4 electrons in its outer most shell so it needs 4 more electrons to complete its octet and attains the stability. Hydrogen has 1 electron in its outer most shell and it needs only 1 electron to attain stability so, each germanium will combine with 4 hydrogen atoms and thus forming 
molecule which is stable in nature.
Hence, is the formula of the hydride formed by germanium.
Arrhenius' Law relates activation energy, Ea, rate constant, K, and temperature, T as per this equation:
K (T) = A * e ^ (-Ea / RT), where R is the universal constant of gases and A is a constant which accounts for collision frequency..
Then you can find the ration between K's at two different temperatures as:
K1 = A * e ^ (-Ea / RT1)
K2 = A* e ^(-Ea / RT2)
=> K1 / K2 = e ^ { (-Ea / RT1) - Ea / RT2) }
=> K1 / K2 = e ^ {(-Ea/ R ) *( 1 / T1 - 1 T2) }
=> K1 / K2 = e^ { (-205,000 j/mol / 8.314 j/mol*k )* ( 1 / 505K - 1/ 485K) }
=> K1 / K2 = e ^ (2.0134494) ≈ 7.5
Answer: 7.5
