When a system moves from A state along path I to B state, it releases heat of 100 J and obtains 50 J work at the same time; when the system does 80J work from A state along path Ⅱ to B state, then Q is（ ）
A: 70J
B: 30J
C: －30J
D: －70J
A: 70J
B: 30J
C: －30J
D: －70J
举一反三
- DU = 100 J is for a system that gives off 100 J of heat and ( ) A: does no work B: does 200 J of work C: has 100 J of work done on it D: has 200 J of work done on it.
- When the initial state and the final state are fixed, "the sum of work and heat" is the state function.
- According to the author, Amanda Ripley fails to note that students' performance in exams varies from state to state. A: A B: B C: C D: D E: E F: F G: G H: H I: I J: J K: K L: L M: M N: N
- 30、设有语句int a[2][3]，下面哪一种不能表示元素a[i][j] ________A、*( a[i] + j )B、*(*( a+ i ) + j )C、*( a + i*3 + j )D、*( *a + i*3 + j )
- 执行语句k=30;j=k++;后k和j的值分别为(<br/>) A: k=30,j=30 B: k=30,j=31 C: k=31,j=30 D: k=31,j=31