问题 多选题

两种氧化物的固体混合物共5.6g,跟7.3%的盐酸100g恰好完全反应,则该混合物可能是(  )

A.MgO和ZnO

B.CaO和CuO

C.MgO和CuO

D.CaO和MgO

答案

设跟7.3%的盐酸100g恰好完全反应的氧化物的化学式为RO,R的相对原子质量为x,则化学方程式为:

RO+2HCl=RCl2+H20

x+16,73

5.6g,7.3%×100g

x+16
73
=
5.6g
7.3%×100g

解之得:x=40,

故两种氧化物中,金属的相对原子质量应该一个大于40,一个小于40,

A、Mg的相对原子质量为24<40,Zn的相对原子质量为65>40,故A适合;

B、Ca的相对原子质量为40,Cu的相对原子质量为64,不满足一个大于40,一个小于40的要求.故B不适合;

C、Mg的相对原子质量为24<40,Cu的相对原子质量为64>40,故C适合;

D、Ca的相对原子质量为40,Mg的相对原子质量为24<40,故D不适合.

故选AC.

单项选择题

Passage One

Discussion of the assimilation of Puerto Ricans in the United States has focused on two factors: social standing and the loss of national culture. In general, excessive stress is placed on one factor or the other, depending on whether fine commentator is North American or Puerto Rica. Many American social scientists, such as Oscar Handlin, Joseph Fitzpatrick, and Oscar Lewis, consider Puerto Ricans as the most recent in a long line of ethnic entrants to occupy the lowest rung on the social ladder. Such a "socio-demographic" approach tends to regard assimilation as a benign process, taking for granted increased economic advantage and inevitable cultural integration, in a supposedly egalitarian context. However, this approach fails to take into account the colonial nature of the Puerto Rican case, with this group, unlike their European predecessors, coming from a nation politically subordinated to the United States. Even the "radical" critiques of this mainstream research model, such as the critique developed in Divided Society, attach the issue of ethnic assimilation too mechanically to factors of economic and social mobility, and are thus unable to illuminate the cultural subordination of Puerto Ricans as a colonial minority.

In contrasts, the "Colonialist" approach of island-based writers such as Eduardo Seda-Bonilla, Manuel Maldonado-Denis, and Lius Nieves-Falcon tends to view assimilation as the forced loss of national culture in an unequal contest with imposed foreign values. There is, of course, a p tradition of culture accommodation among other Puerto Rican thinkers. The writings of Eugenio Fernandez Mendez clearly exemplify this tradition, and many supporters of Puerto Rico’s commonwealth status share the same universalizing orientation. But the Puerto Rican intellectuals who have written most about the assimilation process in the United States all advance cultural nationalist views, advocating the preservation of minority cultural distinctions and rejecting what they see as the subjugation of colonial nationalities.

This cultural and political emphasis is appropriate, but the colonialist thinkers misdirect it, overlooking the class relations at work in both Puerto Rican and North American history. They pose the clash of national cultures as an absolute polarity, with each culture understood as static and undifferentiated. Yet both the Puerto Rican and North American traditions have been subject to constant challenge from cultural forces within their own societies; forces that may move toward each other in ways that cannot be written off as mere "assimilation". Consider, for example, the indigenous and Afro-Caribbean traditions in Puerto Rican’ culture and how they influence and are influenced by other Caribbean cultures and Black cultures in the United States. The elements of Coercion and inequality, so central to cultural contact according to the colonialist framework, play no role in this kind of convergence of racially and ethnically different elements of the same class.

The Puerto Rican writers who have written most about assimilation do NOT ().

A.regard assimilation as benign

B.resist cultural integration

C.describe in detail the process of assimilation

D.take into account the colonial nature of the Puerto Rican case

单项选择题