Zapisujemy na Twoim urządzeniu to, bez czego serwis nie działa, np. zalogowanie. Plików analitycznych użyjemy tylko za Twoją zgodą. Szczegóły w polityce prywatności.
Baza zadań
Wybierz umiejętność, rok lub poziom trudności. Każde zadanie ma klucz i schemat punktowania.
Pokazujemy tylko poziomy, dla których mamy zadania.
Znaleziono 1476 zadań
Raising the temperature of a reaction mixture by 10 °C can double the rate of reaction, even though the collision frequency increases by only a few per cent. What is the main reason for the large increase in rate? A. The activation energy of the reaction is…
Which expression correctly gives the equilibrium constant for the following reaction? 2 NO(g) + Cl2(g) ⇌ 2 NOCl(g) A. B. C.…
The energy profile of a reaction that occurs in two steps is shown. Which statement is correct? A. Q is a transition state, and the first step is rate-determining. B. Q is an intermediate, and the first step is rate-determining. C. Q is an intermediate, and…
The equation for a reaction between gases X and Y is: 2 X(g) + Y(g) ⇌ 2 Z(g) At equilibrium at 700 K the concentrations of X, Y and Z are 0.50 mol dm−3, 0.40 mol dm−3 and 1.0 mol dm−3 respectively.…
Which reaction is expected to have the largest Arrhenius factor, A, at a given temperature? A. Cl2(g) + Br2(g) → 2 BrCl(g) B. Cl(g) + CH4(g) → HCl(g) + CH3(g) C. C2H4(g) + HBr(g) → C2H5Br(g) D. Cl(g) + Br(g) → BrCl(g)
Which reactions involve the transfer of a proton? I. CH3COOH(aq) + NH3(aq) → CH3COONH4(aq) II. 2 CH3COOH(aq) + Mg(s) → (CH3COO)2Mg(aq) + H2(g) III. CH3COOH(aq) + NaHCO3(s) → CH3COONa(aq) + H2O(l) + CO2(g) A. I and II only B. I and III…
An indicator, HIn, is a weak acid with pKa = 5.0. HIn is yellow and its conjugate base, In−, is blue. HIn(aq) ⇌ H+(aq) + In−(aq) Which statements are correct? I. At pH 2.0 the indicator appears yellow. II. At pH 5.0 the…
The overall reaction during the discharge of a lead–acid battery is: Pb(s) + PbO2(s) + 2 H2SO4(aq) → 2 PbSO4(s) + 2 H2O(l) Which statement is correct? A. The oxidation state of lead in Pb(s) changes from +2 to 0. B. The oxidation state of sulfur…
In a redox titration, dichromate(VI) ions are reduced to chromium(III) ions and iron(II) ions are oxidized to iron(III) ions. Cr2O72−(aq) reduced to Cr3+(aq) Fe2+(aq) oxidized to Fe3+(aq) What volume of…
Two observations are made about the halon CF2ClBr in the stratosphere. Which pair of statements explains the observations? Use section 12 of the data booklet. A. The C−Br bond has the highest bond enthalpy of the three carbon–halogen bonds;…