(各2.5分,共5分).取一定量的Na 2 CO 3 和Na 2 SO 4 混合物溶液与过量盐酸反应,生成2.016 L

王轶列2022-10-04 11:39:540条回答

(各2.5分,共5分).取一定量的Na 2 CO 3 和Na 2 SO 4 混合物溶液与过量盐酸反应,生成2.016 L CO 2 (标况下),然后加入足量的Ba(OH) 2 溶液,得到沉淀的质量为2.33 g。试计算混合物中Na 2 CO 3 和Na 2 SO 4 的物质的量分别为多少。

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(x - 5 - 4)* 6 + 1*5 + 2*4 = (x - 3 - 4 - 1)*3 + 8*3 + 9*4 + 10*1
解得x=29
在数学竟赛中,一共20道题,每答对一题得五分,每答错一题扣2.5分小明得了85分,他答错了几道题?
mzdwq1年前4
fieje 共回答了4个问题 | 采纳率25%
(100-85)÷2.5
5分之3y加2.5分之y加4等于2.4y.0.5分之4x减1.5减0.02分之0.5x减0.08等于0.1分之1.2减x
5分之3y加2.5分之y加4等于2.4y.0.5分之4x减1.5减0.02分之0.5x减0.08等于0.1分之1.2减x加2.
要正确答案,第2个方程要写,原方程化简为,不要错误答案
0.5分之4x减1.5减0.02分之0.5x减0.08等于0.1分之1.2减x加2.
网事虽疯1年前3
奇妙人生 共回答了18个问题 | 采纳率100%
8x-25x-0.08=12-x=2
16x=-13.92
x=-0.87
小玲准备炒一个西红柿鸡蛋的菜,她洗切西红柿用了1.5分,洗葱切葱用了2.5分,敲蛋打蛋用了2分,洗锅2分,把锅烧热1分,
小玲准备炒一个西红柿鸡蛋的菜,她洗切西红柿用了1.5分,洗葱切葱用了2.5分,敲蛋打蛋用了2分,洗锅2分,把锅烧热1分,将油烧热用3分,炒4分,小玲烧好这道菜花了16分.请你巧妙安排,设计出一个顺序,使烧好这道菜的时间最短.
东方之小猪1年前1
一根葱 共回答了14个问题 | 采纳率92.9%
解题思路:根据题干,在把锅烧热及把油烧热的同时,可以进行洗切西红柿和洗切葱花,由此即可设计出.

先把锅洗好,敲打鸡蛋,在把锅烧热及把油烧热的同时,洗切西红柿和洗切葱花,然后可以炒西红柿鸡蛋了.按上面步聚进行只需时间是:

2+2+1+3+4=12(分).
答:按上述顺序烧菜的时间最短,是12分钟.

点评:
本题考点: 最佳方法问题.

考点点评: 此题是合理安排时间的问题,奔着如何安排最能节约时间又不使各个程序相互冲突,进行合理设计,是解决此类题目的中心思想.

解方程:5分之3y+2.5分之(y+4)=2.4y
BUYBIRD1年前3
鹿野仙踪 共回答了20个问题 | 采纳率85%
3/5y+(y+4)/2.5=2.4y
同时乘以5,得
3y+2(y+4)=12y
3y+2y+8=12y
7y=8
y=8/7
7.8千克=()克 3时=()分 300分=()时 2.5分=()秒 1800秒=()分 2时=()秒 3时20分=()
7.8千克=()克 3时=()分 300分=()时 2.5分=()秒 1800秒=()分 2时=()秒 3时20分=()分
lois_8110211年前3
止是一条鱼 共回答了20个问题 | 采纳率100%
7.8千克=(7800)克 3时=(180)分 300分=(5)时 2.5分=(150)秒 1800秒=(30)分 2时=(7200)秒 3时20分=(200)分
游乐场的溜冰滑道如图.溜冰车上坡每分行400米,下坡每分行600米.已知从A点到B点需3.7分,从B点到A点只需2.5分
游乐场的溜冰滑道如图.溜冰车上坡每分行400米,下坡每分行600米.已知从A点到B点需3.7分,从B点到A点只需2.5分.问:AC比BC长多少米?
逗你玩啊1年前0
共回答了个问题 | 采纳率
有一次智力测试中王涛共做了20道判断题他每答对一道题得5分每答错一道题道扣2.5分已知王涛得了85分他打错了几道题?
魅力海南1年前10
风遗言 共回答了11946个问题 | 采纳率0.6%
6道,100—85=15 15➗2.5=6
(2.5分)A、B、C、D、E为初中化学常见五种不同类别的物质,它们之间的关系如下图所示(“—”表示相连的两种物质能发生
(2.5分)A、B、C、D、E为初中化学常见五种不同类别的物质,它们之间的关系如下图所示(“—”表示相连的两种物质能发生反应,“→”表示一种物质转化成另一种物质。反应条件、部分反应物和生成物已略去)。若A、B、C均含有相同金属元素,B→C反应放出大量热,E是相对分子质量最小的物质,请回答下列问题:

⑴请写出物质A、C的化学式:
A ,C
⑵请写出D→E反应的化学方程式 ,该反应的基本反应类型为

upendi_chen1年前1
lanidea 共回答了14个问题 | 采纳率85.7%
⑴ A CaCO 3 Ca(OH) 2
⑵Fe+2HCl===FeCl 2 + H 2 ↑置换反应


试题分析:解答框图式的推断题,要找出解题的突破口,或者说是“题眼”,常见的“题眼”有:特殊的物质颜色,特殊的反应条件及反应现象,甚至特殊的反应类型等,由于A、B、C、D、E为初中化学常见五种不同类别的物质,E是相对分子质量最小的物质,即氢气,是单质,那么可以判断D应为酸,而A、B、C均含有相同金属元素,B→C反应放出大量热,可以推断应该都含金属元素钙元素,A应为碳酸钙,B为氧化钙,C为氢氧化钙,
(1)物质A的化学式:CaCO 3 ,C的化学式:Ca(OH) 2
(2)由于D是酸,E是氢气,所以D→E反应的化学方程式:Fe+2HCl===FeCl 2 + H 2 ↑,该反应的基本反应类型:置换反应
第三部分 阅读理解(共20小题:每小题2.5分,满分50分)阅读下列短文,从每题所给的四个选项A、B、C、D四

第三部分 阅读理解(共20小题:每小题2.5分,满分50分)
阅读下列短文,从每题所给的四个选项A、B、C、D四个选项中,选出最佳选项。
Today, as in every other day of the year, more than 3000 U.S. adolescents will smoke their first cigarette on their way to becoming regular smokers as adults. During their lifetime, it can be expected that of these 3000 about 23 will be murdered, 30 will die in traffic accidents, and nearly 750 will be killed by a smoking-related disease. The number of deaths attributed to cigarette smoking outweighs all other factors, whether voluntary or involuntary, as a cause of death.
Since the late 1970s, when daily smoking among high school seniors reached 30 percent, smoking rates among youth have declined. While the decline is impressive, several important issues must be raised.
First, in the past several years, smoking rates among youth have declined very little. Second, in the late 1970s, smoking among male high school seniors exceeded that among female by nearly 10 percent. The statistic is reversing. Third, several recent studies have indicated high school dropouts have excessively high smoking rates, as much as 75 percent.
Finally, though significant declines in adolescent smoking have occurred in the past decade, no definite reasons for the decline exist. Within this context, the National Cancer Institute (NCI) began its current effort to determine the most effective measures to reduce smoking levels among youth.
36. According to the author, the deaths among youth are mainly caused by __________.
A. traffic accidents B. smoking-related disease
C. murder D. all of these
37. Every day there are over ______ high school students who will become regular smokers.
A. 750 B. 23 C. 30 D. 3000
38. By “dropout” the author means __________.
A. students who failed the examination B. students who left school
C. students who lost their way D. students who were driven out of school
39. The reason for declining adolescent smoking is that __________.
A. NCI has taken effective measures
B. smoking is prevented among high school seniors
C. there are many smokers who have died of cancer
D. none of these
40. What is implied but not stated by the author is that __________.
A. smoking rates among youth have declined very little
B. there are now more female than male smokers among high school seniors
C. high smoking rates are due to the increase in wealth
D. smoking at high school is from low socio-economic backgrounds
就算青蛙吧1年前1
芙蓉绣缨花 共回答了18个问题 | 采纳率88.9%
36-40 BDBDB
小题1:
小题2:
小题3:
小题4:
小题5:
小题6:

(2.5分之x-1)-(1.25分之x)等于1.2
(2.5分之x-1)-(1.25分之x)等于1.2
(2.5分之之x减1)-(1.25分之x)等于1.2怎么算
crs19151年前2
秋风难忘 共回答了20个问题 | 采纳率80%
根据对话的情景,从方框中选择适当的句子完成对话,使对话完整通顺。其中有两项是多余的。(每小题0.5分,共2.5分)
根据对话的情景,从方框中选择适当的句子完成对话,使对话完整通顺。其中有两项是多余的。(每小题0.5分,共2.5分)
A: Leo, I don’t want to cook lunch.
B: 小题1:
A: Good idea! Let’s go.
(They are in the Chinese restaurant.)
C: 小题2:
A: Yes, some rice, fish and vegetables, please.
C: Would you like something to drink?
A: Yes. A glass of orange juice. What about you, Leo?
B: I’d like a glass of water.
C: 小题3:
B: Some jiaozi, please.
C: Would you like some chicken? It ’s very nice.
A: 小题4: That’s all.
C: OK. 小题5:
A. I’d like something to drink.
B. May I help you?
C. No, thanks.
D. What would you like to eat?
E. That’s all right.
F. What about going to that Chinese restaurant?
G. Thank you.
dongdiao1年前1
怀念春天的 共回答了13个问题 | 采纳率69.2%
小题1:F
小题2:B
小题3:D
小题4:C
小题5:G

用括号中所给词的适当形式填空。(2.5分)
用括号中所给词的适当形式填空。(2.5分)
小题1:What ________ you _______ ( do ) from eight to ten yesterday morning ?
小题2: The music_________ ( sound ) great .
小题3:Would you mind ______________ ( not smoke ) here ?
小题4:They learned Japanese by ________( they ) last year .
小题5:Several _________( science ) took part in the important meeting yesterday .
光棍鸡1年前1
zzzeeezzz 共回答了20个问题 | 采纳率85%
小题1:were doing
小题2:sounds
小题3:not smoking
小题4:themselves
小题5:scientists

1961年5月22日发生在智利的8.9级地震是世界上有仪器记录的最大地震.()(2.5分)A、正确B、错误
kogogo1年前1
hixuewawa 共回答了25个问题 | 采纳率100%
可选B,因为2011年3月11日东日本大地震的震级是9级.但我拒绝认可.因为东日本大地震一开始的监测数据显示为8.8级,而不是后来确认的9级.因此也可选A.
小胖期中考试语文的成绩比三门主课的平均分低7.5分,英语比三门主课的平均分低2.5分,那么数学成绩比英语成绩高()风.
wyhh1年前1
ss黃頁 共回答了15个问题 | 采纳率93.3%
设语文为a,数学为b,英语为c
则a=(a+b+c)/3-7.5
c=(a+b+c)/3-2.5
所以a+c=(2a+2b+2c)/3-10
所以b=(a+b+c)-(a+c)
=(a+b+c)/3+10
所以b-c=12.5
根据对话内容选择恰当的句子补全下列对话,其中2项多余。(0.5×5=2.5分)
根据对话内容选择恰当的句子补全下列对话,其中2项多余。(0.5×5=2.5分)
A: Good evening, madam. Welcome to our restaurant.
B: Good evening.小题1:?
A: OK. Here it is.
B: Thank you.
(A few minutes later)
A: 小题2:, madam?
B: Sure. I’ll have noodles and can I have a salad ?
A: Sure. We have green salad, fruit salad and chicken salad. 小题3:?
B: A green salad, please.
A: 小题4:?
B: Yes. Coke, please.
A: OK.Anything else ?
B:小题5:.
A: OK. I’ll be back soon with your food and drink.
孤峰月影1年前1
天上流歆 共回答了12个问题 | 采纳率91.7%
小题1:B
小题2:F
小题3:D
小题4:G
小题5:A

语文考试成绩分析我考了93分,成语填空扣了2.5分,阅读扣了2.5,作文扣了1分,写省略号的意思扣了1分,要写500字左
语文考试成绩分析
我考了93分,成语填空扣了2.5分,阅读扣了2.5,作文扣了1分,写省略号的意思扣了1分,要写500字左右。
wo74nvren1年前1
micbird 共回答了10个问题 | 采纳率70%
几年极?初中的话你作文不错啊!!应该说很好了!小学的话差了点!
数学竞赛有40道题,算对一道给2.5分,算错一道倒扣1.5分,结果王刚得60分,他错了几道题?
超级女生yy1年前1
小猫mm790801 共回答了19个问题 | 采纳率100%
假设王刚40题全部做对,则做错了:
(2.5×40-60)÷(2.5+1.5),
=40÷4,
=10(道),
答:王刚做错了10道.
一、填空1.一个比的比值是2,且前项、后项、比值、三个数之和是11,这个比是():()2.5分之X的倒数是4分之3,X的
一、填空
1.一个比的比值是2,且前项、后项、比值、三个数之和是11,这个比是():()
2.5分之X的倒数是4分之3,X的倒数是()
二、应用题
1.把一个高3分米的圆柱体底面平均分成若干个扇形,然后切开,再拼成一个近似长方体,长方体的表面积比圆柱体增加120平方厘米,求原圆柱体的体积
2.甲乙同时从AB两市相对开出,经过3小时,在离中点18千米处相遇,这时甲乙所行的路程比为2:3,甲乙每小时各行几千米?
yfz0011年前10
西北偏西北 共回答了17个问题 | 采纳率100%
一、
1.6:3=2
2.1/(x/5)=3/4
X=20/3
1/X=3/20
二、
1.由已知,2πRR+2πRH+120=2R*πR+2RH+2πRH
解得RH=120
又H=30
所以R=2
所以V=πRRH=3.14*2*2*30=376.8(平方厘米)
2.设甲速度为X,乙速度为Y,甲乙所行路程比为2:3,因此乙速度快.
两人在距离中点18千米处相遇,因此
3Y-3X=18*2=36
又路程比为2:3,因此
3Y:3X=2:3
解得3Y=108,3X=72
Y=36,X=24
甲每小时行24千米,乙每小时行36千米.
数学竞赛共40题对一题得2.5分错一题扣1.5分小红得了80分对了几题?算式是?
candyania1年前3
菁菁_百合 共回答了22个问题 | 采纳率95.5%
2.5x-1.5(40-x)=80
2.5x-60+1.5x=80
4x=140
x=35
沉积相 求高手多选题 (共13道题)收起12.(2.5分) 重力流形成条件包括:( )。 A、较大的水深 B、足够的坡度
沉积相 求高手
多选题 (共13道题)
收起
12.(2.5分) 重力流形成条件包括:( )。
A、较大的水深
B、足够的坡度和密度差
C、充沛的物源
D、触发机制
13.(2.5分) 重力流的基本类型可根据形成环境和成因特征,划分为( )。
A、泥石流
B、碎屑流
C、海相重力流
D、陆相重力流
14.(2.5分) 滑动、滑塌与沉积物液化的证据有( )。
A、包卷层理
B、平行层理
C、滑塌构造
D、重荷模
15.(2.5分) Wilson(1975)碳酸盐岩综合相模式中的开阔陆鹏相的主要岩石类型有( ) 。
A、富含化石的灰岩
B、砂岩
C、页岩
D、泥灰岩
16.(2.5分) 海水的水动力作用包括以下哪种形式( )。
A、波浪
B、潮汐
C、漩涡
D、海流
17.(2.5分) 下列哪种因素可引起海流运动?( )。
A、地球重力场变化
B、温度变化
C、盐度分布不均
D、降雨
18.(2.5分) 海洋沉积相可划分为( )。
A、滨海相
B、浅海相
C、半深海相
D、深海相
19.(2.5分) 海岸沙丘的沉积特征包括:( )。
A、沉积物细-中粒
B、成熟度低
C、重矿物富集
D、具大型交错层理
20.(2.5分) 后滨亚相的沉积特征包括:( )。
A、具平行层理
B、粒度较沙丘带粗
C、生物介壳凸面朝上
D、磨圆分选较好
21.(2.5分) 前滨亚相沉积特征包括:( )。
A、分选较好
B、冲洗层理发育
C、常见生物扰动构造
D、砾石扁平面倾向指示大海中央方向
22.(2.5分) 临滨亚相沉积特征包括:( )。
A、常发育沿岸沙坝
B、地形越平缓越有利沙坝发育
C、上部发育有大量的泥质沉积物
D、高能沉积区有利于沙坝沉积
23.(2.5分) 在半深海主要沉积类型包括:( )。
A、重力流
B、等深流
C、热对流
D、悬浮沉积
24.(2.5分) 重力流形成特征包括:( )。
A、阵发性
B、含大量悬浮物质
C、杂基支撑
D、具侵蚀作用
zsz611年前1
ww比爱更美好 共回答了11个问题 | 采纳率90.9%
12.ABCD 13.CD 14.ACD 15.暂时不知道答案 16.ABD 17.ABC 18.ABCD 19.ABCD 20.ABCD 21.ABCD 22.暂时不知道答案 23.ABD 24.ABCD
有两个不知道答案 找到了 补给你
小兰和小芳同时从环形跑道上的一点向相反方向走去,小兰每分走65米,小芳每分走75米,经过2.5分相遇.这个环形跑道全长是
小兰和小芳同时从环形跑道上的一点向相反方向走去,小兰每分走65米,小芳每分走75米,经过2.5分相遇.这个环形跑道全长是多少米?
zirui11年前4
yctd_328 共回答了14个问题 | 采纳率92.9%
解题思路:用小兰的速度加上小芳的速度,求出两人的速度和,再乘两人的相遇时间,就是环形跑道的全长.据此解答.

(65+75)×2.5,
=140×2.5,
=350(米).
答:环形跑道全长350米.

点评:
本题考点: 简单的行程问题.

考点点评: 本题的关键是求出两人的速度和,再根据路程=速度×时间这一数量关系解答.

一次数学测验共有20道题,每答对一道题得5分,每答错一道倒扣2.5分.小灿得了85分她答错了几道题?
swordlulj1年前1
xiaoguan08 共回答了16个问题 | 采纳率100%
假设答对了X道,答错了Y道.则:
X+Y=20
2.X*5-Y*2.5=85.


解出这个方程式得
Y=2,X=18.
所以打错了2道题.
小强、小新、小涛参加奥运长跑比赛.小强3分跑950米,小新2.5分跑650米,小涛4分跑1330米,谁最快
rsqr1年前4
wangjie2006 共回答了15个问题 | 采纳率100%
小涛 1330/4>小强 950/3>小新650/2.5