问题 选择题

某同学想用实验证明氯化铁溶液的黄色不是Cl-引起的,设计的下列实验无意义的是(  )

A.将铁丝在氧气中燃烧后观察生成物颜色

B.向氯化铁溶液中滴加适量硝酸银溶液,振荡后静置,溶液黄色未消失

C.向氯化铁溶液中滴加适量的氢氧化钠溶液,振荡后静置,溶液黄色消失

D.观察氯化钠溶液没有颜色

答案

A、铁丝在氧气中燃烧与铁离子、氯离子均无关系,没有意义,A方法错,符合题意;

B、氯化铁溶液中加适量的硝酸银溶液,二者反应生成氯化银沉淀,从而除去了溶液中的Cl-,而溶液黄色未消失,说明溶液的黄色不是Cl-引起的,B方法对;不符合题意;

C、氯化铁溶液中滴加适量的氢氧化钠溶液,二者反应生成氢氧化铁沉淀,从而除去了溶液中的铁离子,溶液黄色消失,说明黄色是铁离子引起的而非Cl-,C方法对;不符合题意;

D、氯化钠溶液没有颜色,而氯化钠溶液中含有Cl-和Na+,就说明Cl-没有颜色,D方法对;不符合题意;

故选A.

综合
填空题

Holidays are special times of (1) from work and other routines. Holidays are often times for celebration, (2) , eating, drinking, travel, and family (3) . In most cultures the scheduling of holidays originally was related to the (4) , the (5) cycle, and (6) . Christmas, December 25, celebrates the (7) of Jesus, but it is not actually known whether Jesus was (8) in the wintertime Over the years Christmas has come to symbolize goodwill and (9) for both Christians and non-Christians, and the (10) of Christmas threatens to replace generosity with greed. Other important holidays in America are Valentine’s Day, St. Patrick’s Day, April Fools’ Day, and (11) . On Valentine’s Day, people give cards, chocolates, flowers, and kisses to their (12) and sweethearts. During Easter Week in late March or early April, Christians remember the death and (13) of Jesus. Although not actually a holiday and has no religious (14) , April Fools’ Day, celebrated on April 1, is a day when people play embarrassing (15) on their fiends and (16) and even on their teachers. In (17) , Labor Day is celebrated on May 1, whereas in (18) and the United States, labor and laborers are honored by a (19) holiday on the first (20) in September.

Holidays are special times of (1) from work and other routines. Holidays are often times for celebration, (2) , eating, drinking, travel, and family (3) . In most cultures the scheduling of holidays originally was related to the (4) , the (5) cycle, and (6) . Christmas, December 25, celebrates the (7) of Jesus, but it is not actually known whether Jesus was (8) in the wintertime Over the years Christmas has come to symbolize goodwill and (9) for both Christians and non-Christians, and the (10) of Christmas threatens to replace generosity with greed. Other important holidays in America are Valentine’s Day, St. Patrick’s Day, April Fools’ Day, and (11) . On Valentine’s Day, people give cards, chocolates, flowers, and kisses to their (12) and sweethearts. During Easter Week in late March or early April, Christians remember the death and (13) of Jesus. Although not actually a holiday and has no religious (14) , April Fools’ Day, celebrated on April 1, is a day when people play embarrassing (15) on their fiends and (16) and even on their teachers. In (17) , Labor Day is celebrated on May 1, whereas in (18) and the United States, labor and laborers are honored by a (19) holiday on the first (20) in September.