【单选题】Suppose that chemical composition is uniform among stars formed from the same cloud of gas and dust, but that chemical composition varies among stars formed from different clouds of gas and dust. Stud...
A.
Algol A and Algol B had the most similar compositions.
B.
Algol A and Algol C had the most similar compositions.
C.
Algol B and Algol C had the most similar compositions.
D.
Algol A, Algol B, and Algol C had the same composition.
【单选题】Suppose that Sphere X had become unfastened from the floor of the vessel during Trials 1 and 7. During which of these trials would Sphere X more likely have undergone the lesser amount of acceleration...
A.
Trial 1, because the magnitude of the electrical force exerted by Sphere Y on Sphere X was greater in Trial 1 than in Trial 7.
B.
Trial 1, because the magnitude of the electrical force exerted by Sphere Y on Sphere X was less in Trial 1 than in Trial 7.
C.
Trial 7, because the magnitude of the electrical force exerted by Sphere Y on Sphere X was greater in Trial 7 than in Trial 1.
D.
Trial 7, because the magnitude of the electrical force exerted by Sphere Y on Sphere X was less in Trial 7 than in Trial 1.
【单选题】氦是太阳 中含量较多的元素,其元素符号为 A . H B . He C . N D . O 28. 引起温室效应的主要物质是 A . SO 2 B . CO C . CO 2 D . 可吸入颗粒物 29. 属于氧化物的是 A . O 2 B . H 2 O 2 C . NaCl D . H 2...
【简答题】(12分)无机化合物可根据其组成和性质进行分类: (1)上述所示的物质分类方法名称是 。 (2)以Na、K、H、O、S、N中任两种或三种元素组成合适的物质,分别填在下表中②③⑥后面。(各空填写一个化学式即可) 物质类别 酸 碱 盐 氧化物 氢化物 化学式 ① HCl ② ③ ④Ba(OH) 2 ⑤Na 2 CO 3 ⑥ ⑦ CO 2 ⑧ Na 2 O ⑨ NH 3 ⑩H 2 O (3)写出⑦转化为...