问题 选择题

在NH4NO3、N2、NO2、NO这4种化合物中N元素的化合价有(  )

A.3种

B.5种

C.4种

D.6种

答案

根据在化合物中正负化合价代数和为零,在NH4NO3中N元素的化合价有两种,设在NH4+和NO3-中氮元素化合价分别是x、一y.x+(+4)=+1,y+(-2)×3=-1,可得x=-3,y=+5;

N2属于单质中N元素的化合价为0;

NO2中,由于氧元素显-2价,根据化合价代数和为零设N元素的化合价为z,则Z+(-2)×2=0,则z=+4;

设NO中N元素的化合价为a,则a+(-2)=0,则a=+2;

故选B.

阅读理解

信息匹配

阅读下列应用文及相关信息, 并按照要求匹配信息.

首先请阅读下列几本儿童书籍的封面及提示性文字:

A.  I Will Hold You Til You Sleep

B.  Two Finger Puppet Magnet Books

C.  I SPY TREASURE HUNT                 

D.  Disney's Little Einsteins

E.  The Wonderful Wizard of Oz                

F.  Learn About Math With Bert & Ernie

以下是5本儿童书籍的介绍.请将它们与之对应的书籍匹配起来.

1.  Based on the new hit animated show airing on the Disney Channel, this new series takes preschoolers

along on the thrilling adventures of Leo, June, Quincy, and Annie, whose missions are illustrated with

beautiful, fullcolor photos.EmmyAward winner Susan Ring specializes in writing for children, and has

written for all types of media.Her books for Disney Publishing Worldwide include Winnie the Pooh

Encyclopedias on Animals and Nature; boxed sets of Pixar's Fun with Phonics, featuring Nemo and

Toy Story characters; and the Baby Einstein books.

2.  Here is the rare book that not only expresses a parent's love for their child, but offers a hope for what

that love will become.It begins with a wish at bedtime, as parents hold their children tight and hope their

love will cradle them, safe and sound.It continues through the day their children have grown up, proud

and strong, and can pass that love on to someone else.This is a book that goes beyond a parent's "I love

you" to the generous wish that our children will make the world a better place.

3.  This bestselling book features riddles that send readers searching through 13 photographs with a fun

house theme.Children will love to purse the mystery of the pirate's hidden treasure, narrowing their

search with every delightfully cluttered page.Looking for an additional challenge? Try the extracredit

riddles.

4.  Pooh, Piglet, and the gang from the HundredAcre Wood are here to guide you through some amazing

activities.Just slip one of the pointing puppets onto your finger, and see if you can solve the puzzles inside.

Your puppet will be drawn to the solutions, and your heart will be hooked by the colorful crew! This

book includes 2 magnetic finger puppets.

5.  This exciting new workbook from Sesame Workshop and Learning Horizons is designed so your

child can have fun learning right along with Big Bird and the other friends from Sesame Street! In this

workbook, your child will learn to recognize numbers, count and match sets of like items.Your child will

even begin to add and subtract! A special "think icon" feature calls attention to activities that are

challenging and more advanced.A special Explore More Feature provides several easytodo home

activities to extend learning in practical and fun ways.

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