问题 选择题

下列叙述正确的是

A.将通入溶液中至饱和,无沉淀产生;再通入,产生沉淀

B.在稀硫酸中加入铜粉,铜粉不溶解;再加入固体,铜粉仍不溶解

C.向溶液中滴加氨水,产生白色沉淀;再加入过量溶液,沉淀消失

D.纯锌与稀硫酸反应产生氢气的速率较慢;再加入少量固体,速率不改变

答案

答案:C

题目分析:A、SO2与CO2对应的酸都比盐酸弱,所以都不与BaCl2反应,所以通入SO2与CO2都不会生成沉淀,故A错误;  B.在稀硫酸中加入铜粉,铜粉不溶解;再加入固体,铜粉会溶解,因为前者提供了氢离子,后者提供了硝酸酸离子,相当于有了硝酸,硝酸具有强氧化性能和铜发生反应,错误;  C.向溶液中滴加氨水,产生白色沉淀是氢氧化铝,再加入过量溶液,该物质能电离出氢离子,酸性较强,又溶解了氢氧化铝沉淀,正确; D.纯锌与稀硫酸反应产生氢气的速率较慢;再加入少量固体后,有铜置换出来,形成了锌铜原电池加了反应速率,错误;

多项选择题
单项选择题

Phyllis Wheatley is regarded as America’s first black poet. She was born in Senegal, Africa, about 1753 and brought to America aboard a slave ship at about the age of seven. John and Susannah Wheatley bought her for three pounds at a slave auction in Boston in 1761 to be a personal servant of Mrs. Wheatley. The family had three other slaves, and all were treated with respect. Phyllis was soon accepted as one of the family, which included being raised and educated with the Wheatley’s twin 15-year-old children, Mary and Nathaniel. At that time, most females, even from better families, could not read and write, but Mary was probably one of the best educated young women in Boston. Mary wanted to become a teacher, and in fact, it was Mary who decided to take charge of Phyllis’s education. Phyllis soon displayed her remarkable talents. At the age of twelve she was reading the Greek and Latin classics and passages from the Bible. And eventually, Mrs. Wheatley decided Phyllis should become a Christian.
At the age of thirteen Phyllis wrote her first poem. She became a Boston sensation after she wrote a poem on the death of the evangelical preacher George Whitfield in 1770. It became common practice in Boston to have" Mrs. Wheatley’s Phyllis" read poetry in polite society. Mary married in 1771, and Phyllis later moved to the country because of poor health, as a teacher and caretaker to a farmer’s three children. Mary had tried to interest publishers in Phyllis’s poems but once they heard she was a Negro they weren’t interested.
Then in 1773 Phyllis went with Nathaniel, who was now a businessman, to London. It was thought that a sea voyage might improve her health. Thirty-nine of her poems were published in London as Poems on Various Subjects, Religious and Moral. It was the first book published by a black American. In 1775 Phyllis wrote a poem extolling the accomplishments of George Washington and sent it to him. He responded by praising her talents and inviting her to visit his headquarters. After both of her benefactors died in 1777, and Mary died in 1778, Phyllis was freed as a slave. She married in 1778, moved away from Boston, and had three children. But after the unhappy marriage, she moved back to Boston, and died in poverty at the age of thirty.

According to the passage, an unusual feature of Mary was that she ______.

A.was not much older than Phyllis

B.wanted to become a teacher

C.was comparatively well educated

D.decided to take charge of Phyllis’s education