Thế nào là gương cầu lõm

Based on its type of chemical bond, which of the following has the highest boiling point? potassium chloride ethyl alcohol water ammonia

An air standard cycle with variable specific heats is executed in a closed system and is composed of the following four processes. 1-2 isentropic compression 100 kpa and 22°c to 600 kpa 2-3 v=constant heat addition to 1500 k 3-4 isentropic expansion to 100 kpa 4-1 p=constant heat rejection to initial state (a) show the cycle on p-v and t-s s (b) calculate the net work output per unit mass (409 kj/kg) (c) determine the thermal efficiency (47.9%)

What is offspring? why does a longer life span mean a higher chance of producing offspring?