方程5x+3=28的解是[ ]
A.x=3
B.x=4
C.x=5
答案:C
已知在298K时下述反应的有关数据:
C(s)+1/2 O2(g)=CO(g) △H1 = -110.5kJ/mol,
C(s)+O2(g)=CO2(g) △H2= -393.5kJ/mol ,
则C(s)+CO2(g)=2CO(g) 的△H为 [ ]
A.+283.5kJ/mol
B.+172.5kJ/mol
C.-172.5kJ/mol
D.-504 kJ/mol
能够承受自船首方向的风、流推力和倒车的拉力,防止船位向后移动及外张的缆绳是:()
①、头缆;②、尾缆;③、前倒缆;④、尾倒缆;⑤、横缆
A.①、④
B.②、③
C.①、③、④
D.②、③、⑤