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21 tháng 1 2022

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19 tháng 1 2022

\(m_{NaOH}=40.10\%=4g\)

\(\rightarrow n_{NaOH}=4:40=0,1mol\)

\(m_{HCl}=73.15\%=10,95g\)

\(\rightarrow n_{HCl}=10,95:36,5=0,3mol\)

PTHH: \(NaOH+HCl\rightarrow NaCl+H_2O\)

              0,1               0,1            mol

Lập tỉ lệ \(\frac{n_{NaOH}}{1}=\frac{0,1}{1}< \frac{n_{HCl}}{1}=\frac{0,3}{1}\)

Sau phản ứng thì NaOH hết và HCl dư

\(\rightarrow n_{HCl\text{phản ứng}}=n_{NaCl}=n_{NaOH}=0,1mol\)

\(\rightarrow n_{HCl\text{dư}}=n_{HCl}-n_{HCl\text{phản ứng}}=0,3-0,1=0,2mol\)

\(\rightarrow m_{HCl\text{dư }}=0,2.36,5=7,3g\)

\(m_{NaCl}=0,1.58,5=5,85g\)

\(\rightarrow\%m_{HCl\text{dư }}=\frac{7,3}{40+73}.100\%\approx6,46\%\)

\(\%m_{NaCl}=\frac{5,85}{40+73}.100\%\approx5,18\%\)

nFe=1 mol
1 mol Fe có N=1.6,02*1023"nguyên tử Fe
1 nt Fe có 26 hạt p, 30 hạt n, 26 hạt e
thì N nt Fe có x hạt p, y hạt n, z hạt e
tam suất tìm x,y,z
b) dựa vào dữ kiện câu a
trong 56 g Fe có z hạt e
trong 1000 g Fe có t hạt e

4 tháng 10 2021

1000G có Fe có t hạt e

TL

HT

Tổng số các loại hạt proton, nơtron và electron của X là 49

p + n + e = 49  hay 2p + n = 49    (1)

Tổng số hạt không mang điện bằng 53,125%  số hạt mang điện

n = 53,125% (p+e) hay n = 53,125%.2p   (2)

Từ (1), (2) ta có p = e = 16 , n =17

4 tháng 10 2021

Tổng số các loại hạt proton, nơtron và electron của X là 49

p + n + e = 49  hay 2p + n = 49    (1)

Tổng số hạt không mang điện bằng 53,125%  số hạt mang điện

n = 53,125% (p+e) hay n = 53,125%.2p   (2)

Từ (1), (2) ta có p = e = 16 , n =17

4 tháng 10 2021

Đồng vị  các biến thể của một nguyên tố hóa học, trong đó hạt nhân nguyên tử có cùng số proton nhưng có chứa số neutron khác nhau và do đó có số khối khác nhau.

4 tháng 10 2021

Đồng vị là các biến thể của một nguyên tố hóa học, trong đó hạt nhân nguyên tử có cùng số proton nhưng có chứa số neutron khác nhau và do đó có số khối khác nhau

3 tháng 10 2021

1. SO2 + H2O ---> H2SO3

Na2O + H2O ---> 2NaOH

2. CuO + 2HCl ---> CuCl2 + H2O

Na2O + 2HCl ---> 2NaCl + H2O

3. CuO + H2SO4 ---> CuSO4 + H2O

Na2O + H2SO4 ---> Na2SO4 + H2O

4. 2NaOH + SO2 ---> Na2SO3 + H2O

Question 1: Where the adverb of frequency " always" go in the following sentence: (A) My father (B)go (C) to work (D) on time. *0 pointsABCDQuestion 2: Put the verb into the correct form: Nam and his father........... (always/ play) tennis every afternoon. *0 pointsalways playsplays alwaysalways playplay alwaysQuestion 3: When do we use Present Continuous? Choose 2 answers in this question. *0 pointsTo talk about an action that's happening nowto talk about an action that happens regularlyto...
Đọc tiếp

Question 1: Where the adverb of frequency " always" go in the following sentence: (A) My father (B)go (C) to work (D) on time. *

0 points

A

B

C

D

Question 2: Put the verb into the correct form: Nam and his father........... (always/ play) tennis every afternoon. *

0 points

always plays

plays always

always play

play always

Question 3: When do we use Present Continuous? Choose 2 answers in this question. *

0 points

To talk about an action that's happening now

to talk about an action that happens regularly

to talk about an action that's happening in the future

Question 4: When do we use Present Simple? *

0 points

We use the Present Simple to talk about something that happens regularly or repeatedly.

We use the Present Simple to talk about something that is happening now or around now.

Question 5: Put the verb into the correct form: My dad.........(be/ water) flowers in the garden. *

0 points

are watering

is waters

is watering

are water

Question 6: If the verb is Positive in the statement, the tag question is ........ *

0 points

Positive

Negative

Question 7: Where the adverb of Frequency " not often" should go in the following sentence: (A)Grade 7 (B) is(C) late (B) in every Ms Thuy's lesson. *

0 points

A

B

C

D

Question 9: Put the verb into the correct form: How ......your sister..........(go) to school? *

0 points

How does your sister go to school?

How do your sister go to school?

How does your sister goes to school?

How do your sister goes to school?

Question 10: Put the verb into the correct form: Watch out! The car (be/come) *

0 points

is coming

is to come

is comes

are coming

Question 11: The film we saw last night was boring, .........? *

0 points

weren't it

wasn't it

aren't they

Question 12: Fill in the blank: You.......pay your energy bill today or they will cut off the power. *

0 points

should

had better

ought to

Question 13: Fill in the blank: You ......do your homework now so you have no homework in the evening. *

0 points

ought to

had better

should

Question 14: Fill in the blank: You......be nice to your brother. *

0 points

ought to

should

had better

Question 15: Fill in the blank: There's no hope in this situation, ......? *

0 points

isn't there

is there

are there

Question 16: When Subject=Everybody, Everyone, Nobody, Somebody, subject of Tag question=.... *

0 points

It

They

Option 3

Question 17: When Subject=Everything, Something, Nothing---> Subject of Tag question=..... *

0 points

they

it

Question 18: Fill in the blank: Everybody in Grade 7 are taking the Mid-term test on 10th, October,......? *

0 points

isn't it

isn't they

aren't they

Question 19: If the verb is Negative in the statement, Tag Question is......

0 points

Negative

Positive

Question 20: Fill in the blank:I am also beautiful,.......? *

0 points

aren't I

am not I

isn't I

Question 21:Fill in the blank: You aren't a doctor, .......? *

0 points

are you

aren't you

is you

Question 22: The following statement is True or False: We always use "contraction" like ' aren't" instead of " are not" in Negative tag questions. *

0 points

True

False

Question 23: Where the adverb of frequency " sometimes" should go in the following sentence: (A) I (B) go(C) shopping(D) in Vincom Mega Mall. Choose 2 answers. *

0 points

A

B

C

D

Question 24: Put the verb into the correct form: My father always (drive) to work but today he (take) a taxi to work. *

0 points

drives/takes

is driving/ is taking

drives/is taking

Question 25: Put the verb into the correct form: Nam (always/make) noisy while I am sleeping. I make me annoyed. *

0 points

is always making

always makes

Question 26: Put the verb into the correct form: I (take part in) Nam's birthday party tomorrow night. *

0 points

am taking part in

are taking part in

take part in

Question 27: Choose the correct tag question: The weather is dread,....? *

0 points

isn't weather

is it

isn't it

is weather

Question 28: Choose the correct tag question: Nam is a excellent cook,.......? *

0 points

is Nam

isn't Nam

isn't he

is he

Question 29: Choose the correct modal of advice in the following sentence: It is going to rain. You..... take a umbrella or you will get wet. *

0 points

should

had better

ought to

Question 30: The following statement is True or False: " Ought to" is rarely used in the Negative sentence or Question *

0 points

True

False

Question 31: Where the tag questions should go in the sentence? *

0 points

At the beginning of sentence

In the middle of sentence

At the end of the sentence

Question 32: Put the verb into the correct form: Ms Thuy (teach) NPTA now. *

0 points

is teaching

teaches

Question 33: Use the given words to complete the sentence: Ha/always/ cycle to school. *

0 points

Your answer

Question 34: Use the given words to complete the sentence: Grade 7 (take) /the Mid-term test/10th October *

0 points

Your answer

Question 35: Rearrange the following sentence: Huyen/playing/ in the school yard./ is/ basket ball/Now *

0 points

Your answer

Question 36: Use the given words to complete: She's pretty,......? *

0 points

Your answer

Question 37: Nam did all his homework, .......? *

0 points

Your answer

Question 38: What modal of advice is suitable for the following sentence: You..........call your mother more often because she misses you so much. *

0 points

Your answer

Question 39: Put the verb into the correct form: There(be)____________________animals in the circus *

0 points

is

are

Question 40: Put the verb into the correct form: Ha never(go)_________________fishing in the winter but she always (do)_____________it in the summer. *

0 points

1
3 tháng 10 2021

ko hiểu

8 tháng 10 2021

Nguyên tử \(B\) có tổng số hạt là \(21\):

\(2p+n=21\) \(\left(p=e\right)\)

Số hạt không mang điện chiếm \(33,33\%\):

\(n=33,33\%\)

\(\Rightarrow\hept{\begin{cases}p=e=7\\n=7\end{cases}}\)

Vậy  trong nguyên tử \(B\) có: \(\hept{\begin{cases}p=7\\e=7\\n=7\end{cases}}\)