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6 tháng 7 2021

Viết các công thức hoá học sau :

Asenic pentaflorua - AsF5

Asin - AsH3

Axton - (CH3)2CO

Photphin - PH3

Photphoran - PH5

Lưu huỳnh hexaflorua - SF6

~HT~

6 tháng 7 2021

- AsF5

- AsH3

2CO

- PH3

- PH5

- SF6

28 tháng 1 2022

a. \(M_B=11,5.M_{He}=11,5.4=46g/mol\)

\(\rightarrow n_B=\frac{m}{M}=\frac{4,6}{46}=0,1mol\)

\(\rightarrow V_B=n.22,4=0,1.22,4=2,24l\)

b. Trong một mol A: 

\(m_C=46.52,174\%\approx24g\)

\(\rightarrow n_C=\frac{m}{M}=\frac{24}{12}=2mol\)

\(m_H=46.13,043\%\approx6g\)

\(\rightarrow n_H=\frac{m}{M}=\frac{6}{1}=6mol\)

\(m_O=46-6-24=16g\)

\(\rightarrow n_O=\frac{m}{M}=\frac{16}{16}=1mol\)

Vậy CT của A gồm: 2C và 6H và 1O

Vậy CT của A là \(C_2H_6O\)

c. \(n_A=\frac{m}{M}=\frac{6,9}{46}=0,15mol\)

Trong 0,15mol A:

\(n_C=2n_A=0,3mol\)

\(\rightarrow m_C=n.M=0,3.12=3,6g\)

\(n_H=6n_A=0,9mol\)

\(\rightarrow m_H=n.M=0,9.1=0,9g\)

\(\rightarrow m_O=6.9-0,9-3,6=2,4g\)

27 tháng 1 2022

Đặt \(CTDC=C_xH_yO_z\)

\(\%m_O=100\%-\left(76,596\%+6,385\%\right)=17,019\%\)

Có tỉ lệ \(x:y:z=76,596:12:6,385:1:17,019:16=6,383:6,385:1,064=6:6:1\)

Vậy CTHH là \(C_6H_6O\)

Read the passage about some future predictions and answer the questions.Circle A, B, C or D. (1,0 pt)Dr Pearson, a futurologist believes in 2045 buildings will be made from concreteplastics and shape-changing materials that can heal themselves and the builders will havesuper-strength skeletons creating half-man, half-machine workers. There will be a need fornew kinds of elevators using magnetic systems. By mid-century, buildings will be miles tall and some may be so large that theircapacity...
Đọc tiếp

Read the passage about some future predictions and answer the questions.
Circle A, B, C or D. (1,0 pt)
Dr Pearson, a futurologist believes in 2045 buildings will be made from concrete
plastics and shape-changing materials that can heal themselves and the builders will have
super-strength skeletons creating half-man, half-machine workers. There will be a need for
new kinds of elevators using magnetic systems. 
By mid-century, buildings will be miles tall and some may be so large that their
capacity enables them to function as small cities in their own right. As these buildings rise
through the clouds, windows will be replaced by reality virtual screens so people can
choose any view they like. However, lack of exposure to pathogens will cause more
allergies. Due to health concerns, scents, candles, incense are also likely to be more strongly
regulated, added Dr Pearson. 
28. When does Dr Pearson make these predictions?
  A. now B. in 2045 C. after 2045 D. before 2045
29. What can future buildings do?
    A. change shapes B. use machines C. self-heal D. create machines
30. What is TRUE about future buildings?
  A. They will be very big. B. They will be very tall.
  C. They will be very modern. D. They will be very old
31. What will cause more allergies?
    A. incense B. pathogens C. candles D. allergies
32. A futurologist is someone who _____________ the future.
    A. believes in B. predicts C. adds to D. builds

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Rewrite the following sentences, stay the same meaning of the first sentences.
(1,0pt)
33. People will decorate their houses to welcome New Year.
Their houses……………………………………………………………..………………
34. The distance between my house and school is about 2 kms
It’s ………………………………………………………………………………………
35. These are her shoes. (hers)
 These……………………………………………………………………………………
36. My brother often stayed up late to watch TV when he was fifteen. (used )
 My brother used………………………………………………………………….…….…
37. Be careful or you’ll fall off your bicycle. (If)
If …………………………………………………………………………………………..

0
27 tháng 1 2022

\(M_{hh}=2.17,2=34,4g/mol\)

Khối lượng hỗn hợp là: \(m_{1hh}=n_{hh}.M_{hh}=0,1.34,4=3,44g\)

Đặt \(\hept{\begin{cases}x\left(mol\right)=CO\\y\left(mol\right)=O_2\end{cases}}\)

Có \(\hept{\begin{cases}x+y=0,1\\28x+32y=3,44\end{cases}}\)

\(\rightarrow\hept{\begin{cases}x=-0,06\\y=0,16\end{cases}}\)

Bạn xem lại đề nhé

27 tháng 1 2022

Đặt \(\hept{\begin{cases}a\left(mol\right)=n_{H_2}=n_{O_2\left(A\right)}\\2b\left(mol\right)=n_{Cl_2}\\3b\left(mol\right)=n_{O_2\left(B\right)}\end{cases}}\)

\(\overline{M_A}=\frac{2a+16.2a}{a+a}=\frac{34a}{2a}=17g/mol\)

\(\overline{M_B}=\frac{2b.71+3b.16.2}{2b+3b}=\frac{238b}{5b}=47,6g/mol\)

\(\rightarrow d_{A/B}=\frac{17}{47,6}=\frac{5}{14}\approx0,36\)

5 tháng 7 2021

Trả lời :

Bạch kim (IV) oxit - PtO2

Niobi (V) oxit - Nb2O5

Photpho pentaflorua  - PF5

Crom (III) nitrua - CrN

~HT~

5 tháng 7 2021

CTHH lần lượt là : \(PtO_2,Nb_2O_5,PF_5,CrN\)

7 tháng 7 2021

Trả lời :

Bạch Kim (IV) oxit - PtO2

Niobi (V) oxit - Nb2O5

Photpho pentaflourua - PF5

Crom (III) nitrua - CrN

~HT~

5 tháng 7 2021

H2CO3

5 tháng 7 2021

h2co3 nha

HCN NH3 • H2O NH4CN H2O

nếu sai thì cho mk xin lỗi nha