C6,u 26. Cho h6n ho-p bdt rin A chria MgSOa, SrCO3, FeCO3, FeS, CuS v2ro dung dich HCI du, ch6t kh6ng tan chria
, ,.!
Gidi: duy nhdt CuS kh6ng tan trong dung dich axit; MgSO7 tan kh6ng phan irng, SrCO3, tan vi phan tfug tqo khi cdcbonic vd mrdi nn SrCl2, FeCOt, tan do phitn drng tqo khi cricbonic vd muiji tan FeCl2, FeS, tan do phan {rng tao khl
H2S vit mu6i lan FeCl2.
CAu27. Nho tt tir cho dt5n du dung djch NH3 vdo ciic dung dich ri6ng biet chf a AlC13, BeC12, FeC13, CuCl2, MgC12 thu dugc kiit tua X. Thu lAy kCt tua X rOi cho viro dung dich NH4CI du thu dugc chAt rin V. SO hq? ch6t trong Y c6 the la
Giti: chi c6 Mg(OH)2 tan trong NH{l n€n cdn l€ti 3 chiit kh6ng tan td Al(OH)3, Be(OH)2 vit Fe(OH)3.
Cltric ctic em t[ch tuj dwqc nhiiu kiih tht?c vir kirth rtghiQnt bi ich qua kjt thi ndy!
@ Kh6i Chuy6n Lf - Dai hqc Khoa hgc Tg'nhi6n - DHQGHN.
Phdng 103, nhir C3, KTX ME Tri, 182 - Lúóng Th6 Vinh, Thanh Xudn, Hh Ngi (04 38543071).
TRTIONG TIIPT CTTUYTN
Ma od: tbq
pnAN cHUNG cno rAr cA rrti SINH (40 cau)
Cflu l: Triphdnrmg: Fe(lrtrO3)2 + AgNO3 ---+ FeG.lO:)r + Ag.
rrroN HoA HQC
Thdi gian: 90 pkit
Phdt bi6u ndo dudi đy ld dring ?
Ạ Fe2* c6 tinh oxi hol manh i-on Fe3*. B. Fe3* c6 tinh oxi horl m4nh hon Ag*. C. Ag* c6 tinh kh& m4nh hon Fe2*. D. Fe2* khu dugc Ag*.
Ciu 2: Ctro tOOrl dung dich h6n hqp CuSOn llul ya Al2(SO4b l,5M t6c dqng vdi drrnc '{ich }ll{i cú lqc l6y k-6t t'i:
dem nung Ai5n ktrOi tuqtrg khOng aOitfru <luqc ch6t rin c6 kh5i luqng ld
A, 15,3 gam. B.30,6 gam. C.23,3 gam. D:8,0 gam'
Cf,u 3: X m4ch hd c6 c6ng ttuic CrHv. Mpt binh c6 dung ticft trOng dtii^chfta hdn. hq,p khi"gdm X ve !1 du O t500C
J uo ru6t zut.. B4t tia tril aien a6 oot ch6y X sau d6 Jua binh ud l50oc, 6p suAt binh v6n li 2atm. Nguoi ta trQh 9,6 gam X v6ihictro rti-"fro qufUintt agng Ni nung n6ng (H = 100%) thi thu iuqc hdn hep Ỵ Kh6i luqng moltrung binh crla Y ld
Ạ49,5. 8.42,5. c.46,5. D.52,5-
C6u 4: bno x li mQt aminoaxir. Khi cho 0,01 molX t6c dung v6i HCI thi dtrng h6t g0ml.dung dich HCI 0,125M vd
thu dugc 1,g35 gam ruOitt1un. Khi cho 0,bl molX tic dgng v6i dung dich NaoH thi cAn dtrng 25 gam dung dich NaOH 3,2oẠ C6ng thirc c6u t4o cia X ld
Ạ NHzCrHs(COOH)2.
c. NHzCTFI6COOH.
B. (NH2)2CrHsCOOH. D. OrH2)2CsHqCOOH' Cf,u 5: Cho phin img: Cu + ff + NO; ---+ Cu2* + NO + HzO
Tting c6c hq s6 cAn bing (t6i giin, c6 nghTa) ctia phan ung tr€n li
Ạ22. 8.23. c.28. D. 10.
Ciu 6: Hoi tan hoin toin m ganhbn hqp X (giim Al, Fe, Zn) bing dung dich HCI dụ Dung dich thu dugc sau phin frng ting l€n so vdi ban diu (m - 2) gurn. ftroi lugng ( ga*) mu5i clorua t4o thdnh trong dung dlch la (adsbygoogle = window.adsbygoogle || []).push({});
Ạm + 73. tr. 6 + 35,5. (. ry1 + 36,5. D' m + 71'
Ciu 7: Dun n6ng 7,6 gam hdn hqp X gdm C2H2, C2Llavd H2 trong binh kin vdi x0c t6c Ni thu dugc h5n hqp khi Ý E5t chdy hodn, tJdn-hón hqp y, dtn san phAm rhil lll dusc lin lust qua binh I dsng H2Soa đc, binh 2 dwrg
căoH)z du th6y ktroi luqng binh I t6ng 14,4 gam. I(h6i lugng t6ng l€n d binh 2 li
Ạ22,0 gam. B. 35,2 gam. C.6,0 gam. D' 9,6 gam'
Cf;u g: Cho mQt lugng sit du tan Long dung dich HNOr lodng thu dugc dung dich X c6 mdu nAu nh4t. ChAt tan
trong dung dich X lA
Ạ r.NOr)2, Fe(NO3)3. B. Fe(NO3)2. C. Fe(NOr)2, HNO3' 9' Fe(NO)3,HYOt'.
-,
C6u 9: Hdn hq p X c6 CzHsOH, CzHsCOOH, CH:CHO trong d6 C2H5OH chi6m50% theo sO mol. D6t ch6y m gam
h5n hqp X.thu duqc 3,06 gam H2Ovd 3,136 lit CO2 (dktc). Mgt kh6c 13,2 gam h6n hqp X thyc hipn phin img triing b4c thiiy c6 p gam Ag ktit tiạ Ci6 tr! cria p ld
. , a,.iJạ 8.8,64. c. 10,8. D.9,72. .
CAu l0: Hoi tan hoin todn 6,0 gam hdn hqp hai kim loqi trong dung dich HCI du th6ylqo ra 4,48lit khi H2 (dktc). Cd c4n dung dich sau phan ung thu dugc m gam mu6i khan. Gi5 ni cua m ld
L.20,6. 8,20,2. c. 13,3. P. 13,1.
CAu ll: Trqn 3 dung dich HCI 0,3M ; HzSOr 0,2M vi H:POr 0,lM voi nhfíng th6 tich bing nhau thu dugc dung dich X'
Dung dich y gdm Na-ort 0,1M vi BăoFr)z 0,2M. Ec trung hoi 300m1 dung dich X cAn vira dri vml dung dich Y, Gi6 tr! cria V ld
Ạ 1000. B. 333,3. c.600. D.200.
Ạ IUUỤ .f,0. JJJ,J.
CAu 12: D6y ndo dudi đy gO* t6i cit cfucchdt d€u Hm e6i riiuịi quy tfm Am ?
Ạ H2NCH2COOH ; CoHsOH ; CoHsNHz B. HzNCHzCOOH; HCOOH ; CHTNHz
c. HrNtcHzlzNHz ; HOOCICHzI+COOH; CoHsOH D. CHTNHz ;(COOFI)z; HOOCICH2I2CH(NHJq99I
Ca;i:;-D5i"iiy rr"ar todn a gam'h5n hqrp cdc este no, don chfrc, m4ch họ Sin phAm chdy ttuqc dAn vio binh dgng ., L, f.. . . r'-. . ^ -,-^ od
--r ^n -,1 rr n +^^ -^ tA- t..* tl .
dung dlch nudc vditong ttr6y khdi hqng biniiGng 6,2 gam. S5 mol COz vA HzO t?o ra lAn lugt li :
Ạ0,05 vi 0,05. 8.0,05 vi 0,1. C.0,1 vi 0,1. D. 0,1 vi 0,15.
Ciu 14: Thiry ph6n m gam tinh bQt, san phAm thu dugc dem l€n men dii sdn xu6t ancol etylic, toin bQ khi COz sinh ra cho oua duns dich CăbFD, dụ thu duoc 750 eam kait tuạ N6u hiQu su6t qui trinh sin xuft ancol etylic le 80% thi
ra cho qua dung dich CăOFt)2 du, thu duọ c 750 gam
;6n xuit ancol etylic, toan bQ khi UUz smh
qui trinh sin xuft ancol etylic le 80% thi m c6 gi6 tri ld
n.b+9,2. 8.486,0. c.759,4- D.607,5.
CAu 15: Oxi ho6 m gam mqt hdn hqrp X gdm fomandehit vi axetandehit bing oxi d di6u kiQn thfch hop thu duọ c h5;hr. p y chi gdm c{c axithftu cọ firurSlnoi cfia Y so v6i X bing x. Khoing bi6n thi€n cta x lA (adsbygoogle = window.adsbygoogle || []).push({});
n. f,:0.*l1,50. B. 1,36<x< 1,53" c. 1,30<x< 1,53. D. 1,36<x< 1,50"
Ạ HOCH2CHzCHzOH vi CH3CH2CH2CH2OIỊ B. CHTCH2CH2OFI vd CHTCHzCH2CIJ'OH.
c' cHrcH2cHzoH vi HocH:cH2cH2cH2oFỊ D. HocH2cH2cHroH vi HocHzcH2cH2cH2oH.
cau 17: X ln hdn hop kim loai Ba vi Al. Hoa tan m gam X vdo t,rsng a"
""0" tiru dugc g,96 lit Hr (dktc). cfrnghod tan Ạ 59,95. m gam X vdo dung dich 8.21,90. NaoH du thi thu dvsciz,3zlft C. 13,70. khi H, ftttrỵ D. cla tri .,iu * la hod tan Ạ 59,95. m gam X vdo dung dich 8.21,90. NaoH du thi thu dvsciz,3zlft C. 13,70. khi H, ftttrỵ D. cla tri .,iu * la
57,50.
ciu l8: PhinrmgT:iYaiyuron^sfr)ngđchungminhtHcdidmcdutaoph6nhrcuagtucoz.ỏ Ạ HoA tan Cu(OH)2 đ chung minh phAn tt cO nhi6u nh6m chric _OH.
lJ' Phan *ng r'riing guoxg đ chung to frong ph6n tu grucozo
c6 nh6m chrrc {Họ
C. Phin ung vdi 5 phAn tu CH3COOH dC chung,inf,
"O 5 nh6m _OH trong ph6n trị
_ D. Tric dpng v6i Na ilti chung minh ph6n hr c6 5 nh6m _OH.
Ciu 19: Chon ciu tlfng trong c6c c6u lau :
Ạ Khi oxi hod ancol nọdcm chric thi thu dugc antlehit.
1. lh*g phrip chung didu ch6 ancol no, aor iturc bac I h cho anken c6ng nuoc.C. Dun n6ng ancol metytic vdi HzSOI d{c d 1700i thu dugc etẹ C. Dun n6ng ancol metytic vdi HzSOI d{c d 1700i thu dugc etẹ
D. Ancol da chirc hoi tan Cu(OFf)2 t4o thinh dune dich miu xanh.
cau 2.0: H6n hgp x c6 2 este don
"ti"ị n ad"g pha; ;il."huụ'Er,o- s,z gam h6n hpp X tric dpng vta hiit vdi l00mt
9::g.{i:! NaoH 0,5M $u {{9c !fu !w Y c6 fiai ancol bdn, cirng s6 nguyen tri cacbon trong ph6n t'ị y kdt hsp vira h€t vdi it hcm 0,06 gam H2. C6ng thfc hii este ld
Ạ C2H3COOCTHT vd CIHTCOOC2H5. B. C2H3COOC3H7 vl CzHsCOOC:Hs. C. C3H5COOCzHs vA CrHrCOOCzHr. D. C#sCOOCrHz vA CrHzCOOCrHs.
CAu 2l: Dey gdm tAt cir c6c ctrdt Adu pfran ung vdi HCO6Flln
Ạ CHiNHz, CzHsOH, KOH, NaCt. B. NH3, K, Cu, NaOH, Oz,Hz. C. AgNO3/lrlHr, CH:NHz, C2H5OH, KOH, NazCOr. D. NazO, NaCi, Fe, CH3OH, CzHsCl.
cau 22: D€ loai cr{c khf : sor, Nrb;tr-trong khf tr,ai cong nghi€p, nguoi ta thuong đn khi thai di qua
dung dich ndo dudi dAy ?
Ạ HCt. B. NaCt. C. NaOH. D. CăOH)2.
ciu 23: TNT (2,4,6-trinitrotoluen) dugc didu chd bing phan img cta toluen vdi h5n rtre go* HNor đc vd HzSoa
drc, trong di€u ki€n dun n6ng. Bi6t hiQu sudt cta toan qua oinn,Eng i;ila;t;.;;g TNT (2,4,6-trinitrototuen)
tao thinh tir 230 gam toluen li
Ạ550,0 gam. P. 687,5 gam. , g. 454,0 gam.. D. 567,5 gam
cau 24: Thu6c thri duy nhdt c6 ttrd iring đ nhan ui6i t .trdt iJ"tto** t ong"i il ffi, nh6n : phenor, stiren, ancot (adsbygoogle = window.adsbygoogle || []).push({});
benzylic li
A dungdichNaoH. B. Nạ C. qu! tim. D. dung dich Br2.CAU 25: Trong c6ng nghiQp, nguoi ta tdng hqrp NH:-theo p'tr"*g tinh hori hgc sau , o - CAU 25: Trong c6ng nghiQp, nguoi ta tdng hqrp NH:-theo p'tr"*g tinh hori hgc sau , o -
Nz(k) + 3Hr(k) --+ 2NH3G)
' Khi ting ndng d0 F{z En hai lin (giti nguycn ndng dQ c,u nri nito vi nhier dO cua phdn ung) thi t6c dQ phdn trng ting
l6n bao nhi6u lAn ?
CAu26: Cho khi CO (du) di qua 5ng sri ctpg hdn hqp X e6m :
hqp rfn ỵ cho y vio dung diih Na6s (d;J,"kh;i;ii;f;;;;
hoAn toin. PhAn khdng an Z gdm :
D. 16 tAn. '
AfzOr,.MgO, Fe3O4, CuO nung n6ng thu duqc h6n
lqi ph6n kh6ng tan Z. GiL sri c6c phrin rhrg x6y ra
Ạ8lin. B.2lAn. C.4lin.
ẠMg, FeO, Cụ B. Mg, Fe, Cụ g. Mg.C,Fe, Cụ D. MgO, Fe3Oa, Cụ
cdu 2T: Xi phong ho-1ho,e1 todn 2,2.2 g"T l'6r hep X s"d; ị; este <rdng il;; ;?;'rh;;;b;;l"s vria h6t 30mrdung dich NaoH lM' Mat kh6c khi a6t ctray honn toan-h6n hsp x ttru oufc'khi cd va hoi Hzo vji grd ucrr ueng dung dich NaoH lM' Mat kh6c khi a6t ctray honn toan-h6n hsp x ttru oufc'khi cd va hoi Hzo vji grd ucrr ueng nhau (d cing diAu kiQn). C6ng thtc cdu eo cria hai csre ll
Á HcoocH2cH2cry va
!coocH(cH3)cH3 B.cn coocHr vi HcooczHs
C. CH3COOCzHs vi CzHsCOOCH: . D. CH3COOCH=-CH2 vA CHr=611aOOCHr
ciu 28: cho 1,0 sum ,Tlsit ti6p xric. vdi oxi mQt thei gianih?thtihd;;l il qu6 t,4t gam. N6u chi r3othdnh mQt oxit sit duy nhdt ttri oxii aO la thdnh mQt oxit sit duy nhdt ttri oxii aO la
Ạ Ferơho{c FezOr. B. FeỌ C. Feror. D. Fe:Or.
pạu J*- o6t ch6y 0,15 gam ch6t hfhr co x-thu- dugc-
922-g^^co2 ; 0,18 gam H2o vi 56rnt Nz (clhc). eịit ti kh6i hsi cria X so vdi oxi li 1,875. C6ng th6c phAn tu cria X li
Ạ CrHroN. B. CzHsN2. C. CH.N. D. CzHoNụ
cau 30: c6 cric lq ri€ng biQt tlpg cdc dung dichthdng mau : AICI3 , zncl2,Mgcl2, Fesoa, Fe(No3)3, Nacl. chi
dirng dung dich ndo dudi d6v đ phen biQt cal re mdt nh# t.e"i -
Ạ Nazcor. B. BăoH)2. c. NaoH. D. NH:.
Ạ (H2N)2C2H2(COOH)2 B. HzNCrHs(COOH)z
c. (H2N)2CzH:COOH D. H2NC2H3(COOH)?
Ciu 33; Cho 18,5 gam hdn hsp X giim Fe, FerƠ t6c dgng vdi 200m1 dung dich HNO: lof;ng dun n6ng vd ktruAy d6ụ Saụkhi phdn trng xiy ra hoin toin dugc 2,24lit khf NO duy nh{t (dktc), dung dich Y vA cdn lai 1,46 gam kim loaị Kh6i lugng mu6itrong Y vi ndng ttq mol cfia dung a;cn mriO3 tn
Ạ 65,34 gam';2,7M. B. 65,34 gam ; 3,2M. C. 48,6 gam;2,7M t. :1," ọ.n, 3,21",1.
Ciu 34: Khi cho ankan X (trong phdn t& c6%C = 83,72) tric dgng voi clo chi thu duọ c 2 đn xu6t monocto dOng phan (adsbygoogle = window.adsbygoogle || []).push({});
cia nhaụ T€n cria X lA
Ạ2-mefylpropan B. 2,3-dimetylbutan C. n-hexan D. 3-metylpentan
CAu 35: Cho 28.,8 gam b6t Cu vdo 200m1 hdn hqrp axit HNO: l,0M vi HzSOq 0,5M thdy tho6t ra V lir khi NO (san
phdm khu duy nhdt, clo o dktc). Gi6 tri cua V li
Ạ2,241it. 8.6,721it. C. 4,49 lit. D. l,l2 lft.
CAu 36: Cho c6c ch6t sau : tinh bdt ; glucozo ; saccarozo ; mantozo, xenlutozọ 56 ch6t kh6ng tham gia phAn ung guong ld
4.2. B. l. c.4. D. 3.
Ciu 37: Cho ancol X tric dung v6i axit Y dụgc este Ẹ Lam bay hoi 8,6 gara E thu ttugc th6 tich hoi d0ng bing th6
tich cria 3,2 gam O2 (do d cirng tti6u kiQn). gitit tvt" > Mỵ C6ng thric
"6u tao cia E li
Ạ CHr=g11COOC2H5. B. HCOOCH=CHCH3.
C. HCOOCH2CH=CH2 D. CHr=6SCOOCH3.
Ciu 38: C6 3 chdt rln ri6ng bi6t : Al, Mg, At2O3. Dung dich c6 thri phAn biQt ba chdt rin tr€n ld
Ạ NaOH. B. HCỊ C. CuClz. D. HNO: loing.
Ciu 39: Hoi tan hodn toin 3,9 gam kali vdo 36,2 gamnudc thu duoc dung dich cd ndng dQ
4.4,04o . B. 15,47Yọ C. ru,Ayọ D. 13,97yọ
CAu 40: Cho c6c ohdt sau : HCI ; NaOH ; Na3PO4 ; NazCOr ; CăOH):. Sd chdt tOi da c6 th6 hm mdm nudc cimg
tam thrii ld I
4.2. B. 3. c.4. D. 5.
PHAN RItNG (lo cau)
Thi sinh chi dugc lAm m$t trong hai phAn Phin l: Theo chucng trinh chuin:
Ciu 4l: C6 mQt lo4ịpolime nhu sau : ...-CHz-CH2-CFI2-CHzlHz-CHz-...
C6ng thric mQt mit xich cta polime ndy lA
Ạ -CHz-CHr B. -CHrCHz-C Hz-C Hz-C Hz-CHz-
Cf,u 32: Cho l00ml dung dich amino axit X 0,2M ulc dung vua di vdi 80ml dung dich NaOH 0,25M. Mqt kh6c l00ml dung dich amino axit tr€n t6c dung vria cfti vdi 80ml dung dich HCI 0,5M. Bi6t X c6 ti khSi hoi so vdi Hz bing 52. C6ng thfc cria X ld
c. -cHz-cHzlHr D. -CHr
Ciu 42: HiQn tuqng quan sdt dugc khi cho dung dlch etylamin tdc dgng vdi dung dich FeCl3 ld Ạ xudt hiQn kiSt tria mdu niu d6. B. c6 kh6imiu tling bay-rạ'
c. xu6t hiQn ktit tfia miu tring. D. c6 khf tho6t ra lail xanh giAy quj Am.
C$u !]: -?_6 *lg hoi 500m1 dung alcn X chua h6n herp HCI O,lM vi HzSOr OJM Jan buo *ieu ml dung dich h6n hqp gdm NaOH 0,3M vd BăOFI)2 0,2M?
11,5 garn CzHsOH (c6 H2SO; dic lim xric tric) thu dugc m gam este (hi0u sudt phen img este ho6 d4t 80%). Gi6tri (adsbygoogle = window.adsbygoogle || []).push({});
crla m ld
Ạ 14,08. 8.12,96. c. 17,6. D.16,2.
Ạ750m1. 8.250m1. C. l25ml. D.500m1.
Ciu 44: Hoi tan 4,0 gam h5n hqrp gdm Fe vi kim loSi X (ho6 tri II, dfmg trudc hidro trong d6y rtiQn ho6) b[ng dung dich HCI du, thu dugc 2,24 lit khi H2 (dktc). oe noa hn 2,4 gam X thi cAn dirng chua A6n isOrt dung dic[ HCI lM. X lA kim lopinAo dudi <f6y ?
Ạ Bạ B. Zn. C. Cạ D. Mg.
9ll +1 OOt mEt lugng Al trong 6J2lito!. Chdt rin thu dyọ c sau phin ung cho f,oi tan hodn toAn vio dung dich HCI thAy thodt ra 6,72litlH2(c6c th6 tich khf do d tfktc). Kh6i luqng Al de dnng ln
Ạ16,2 gam. _ B. 5,4 gam. C. 8,1 gam. D. 10,8 gam.
liun!: Cho x gam hdn hqp bOt c6c kim lo4iNi vd Cu vio dung dich AgNO3 du, khu6y ki cho đn khiphAn rmg kdt thric thu dugc 54 gam kim lgaị M4t kh6c cfing cho x gam hdn hgrp bQt kim loaitr6n vio dung dich CuSO4 du, khu6y kT cho d6n khi pnan ung krit ttuic thu dugc 1i + o,s; gam kim loal. cia tri cfia x la
Ciu 47: Odt cnay hoin todn 2,24lit (dktc) h6n hsp X giim C2Ha vt CaHa thi thri tich khf COz (dktc) vA kh6íluqng hcvi HzO thu duọ c lAn lust Ii
Ạ 3,36 lft vi 3,6 gam, B. 8,96 lit vA 3,6 gam. C.6,7? lft vh 3,6 gam. D. 5,6 litva2,7 gam.
CAu ,18: Nung m gam bQt sit trong oxi thu dugc 3,0 gam h6n hgrp chdt rin X. HoA tan hlit h6n hgrp X trong dung dich HNO3 (du), thoat ri 0,56 lft khi NO (li sin phim khri duy nhdt, do d didu ki6n ti6u chuAn). Gi6 tri c.ia m li
Ạ2,80. 8.2,52. c.2,10. D.4,20.
Ciu 49: Hoi tan hoAn toAn 13,92 gam Fe3Oa blng dung dich HNOr thu duọ c 448m1 khi N*Oy (dktc). N.Oy li khi nio du6i dAy ?
Ạ N:Ọ B. NO2. C. NzOs. D. NỌ
Ciu 50: Trong đy bi6n ho6 :
C:Ho -+ CzHsCl -+ C2H5OH + CH:CHO -+ CHTCOOH -+ CHTCOOCzHs -+ CzHsOH si phin ung ori hod - khri trdn đy bi6n hod tr€n li bao nhi6u ?
Ạ2 8.4 c.3 D.5
PhAn 2: Theo chuang trinh ning cao:
Cdu 5l: H5n hgp X ning 9 garn giim Felor vA Cụ Cho X vdo dung dich HCI du thAy cdn 1,6 gam Cu khdng tan. Khtii lugng Fe:Ơ c6 trong X lA
D.2,32 gam.
Ạ 5,8 gam. 8.7,4 gam. C.3,48 gam.
CAu 52: Criolit c6 cdng th&c phAn tu lA Na:AIFo dugc th€m vio Al2O3 trong qu6 trinh diQn phAn Al2O3 n6ng chiy dr! sdn xudt nh6m vdi lf do chinh li
Ạ IAm tlng ttQ a6n aien cria AlzOr n6ng chiỵ
B. t4o mQt lqp ngln crich đ bAo vQ nhdm ndng chiy khdi bi oxi ho6.C. bio v€ cliQn cgc khdi bi [n m]n-.---- '. C. bio v€ cliQn cgc khdi bi [n m]n-.---- '.