问题 填空题

对知识进行归纳和整理是学习化学的一种重要方法.现有H2、CO、CH4三种气体,将其中任意一种气体与另外二种气体进行比较,指出它们的不同之处:

(1)______.

(2)______.

答案

(1)由两种元素组成,一种元素是氧元素属于氧化物,所以一氧化碳属于氧化物,氢气和甲烷不属于氧化物;

(2)由一种元素组成的纯净物属于单质,由不同元素组成的纯净物属于化合物,所以氢气是单质,一氧化碳和甲烷属于化合物.

故答案为:(1)CO是氧化物,其余不是;(2)H2是单质,其余是化合物(其他合理答案参照给分).

单项选择题
单项选择题

Vienna was one of the music centers of Europe during the classical period, and Haydn, Mozart, and Beethoven were all active there. As the (1) of the Holy Roman Empire (which included parts of present-day Austria, Germany, Italy, Hungary, Czech and Slovakia), it was a (2) cultural and commercial center (3) a cosmopolitan character. Its population of almost 250,000 (in 1800) made Vienna the fourth largest city in Europe. All three (4) masters were born elsewhere, but they were (5) to Vienna to study and to seek (6) . In Vienna, Haydn and Mozart became close friends and influenced each other’s musical (7) . Beethoven traveled to Vienna at sixteen to play for Mozart; at twenty-two, he returned to study with Haydn.

Aristocrats from all over the Empire spent the winter in Vienna, sometimes bringing their private (8) . Music was an important part of court life, and a good orchestra was a (9) of prestige. Many of the nobility were excellent musicians.

Much music was heard in (10) concerts where aristocrats and wealthy commoners played (11) professional musicians. Mozart and Beethoven often earned money by performing in these intimate concerts. The nobility (12) hired servants who could (13) as musicians. An advertisement in the Vienna Gazette of 1789 (14) : " Wanted, for a house of the gentry, a manservant who knows how to play the violin well. "

In Vienna there was also (15) music, light and popular in (16) . Small street bands of wind and string players played at garden parties or under the windows of people (17) to throw (18) money. Haydn and Mozart wrote many outdoor entertainment (19) , (20) they called divertimentos or serenades. Vienna’s great love of music and its enthusiastic demand for new works made it the chosen city of Haydn, Mozart and Beethoven.

2()

A.romantic

B.bustling

C.integrated

D.antique