................................................................................................................................................
............................................................................................................................................. [2]
(c) Scientists investigated the response of stomata to changing carbon dioxide (CO )
Question
Biology
CAIE2023
concentrations in the beach morning glory, I. pes-caprae.
The scientists placed I. pes-caprae plants in chambers. They measured the width of
open stomata (stomatal apertures) after the plants had been exposed to different CO
Question
Biology
CAIE2023
concentrations for 40 minutes. Light intensity and temperature were kept constant.
The relationship between CO concentration and the mean width of stomatal apertures is
................................................................................................................................................
............................................................................................................................................. [2]
(c) Scientists investigated the response of stomata to changing carbon dioxide (CO )
Question
Biology
CAIE2023
concentrations in the beach morning glory, I. pes-caprae.
The scientists placed I. pes-caprae plants in chambers. They measured the width of
open stomata (stomatal apertures) after the plants had been exposed to different CO
Question
Biology
CAIE2023
concentrations for 40 minutes. Light intensity and temperature were kept constant.
The relationship between CO concentration and the mean width of stomatal apertures is
In the future, climate change may reduce water availability and increase atmospheric
CO concentrations in some habitats.
Question
Mathematics
CAIE2022
Vectors a and b are such that |a| = 5, |b| = 12, and a · b = 0.
(a) State what a · b = 0 implies about a and b.
(b) Find |a + b|.
[3 marks]
Physics
Edexcel2022
Which of the following quantities is a vector?
A charge
B mass
C momentum
D time
(Total for Question 7 = 1 mark)
Question
Mathematics
Edexcel2019
*P58306A0328*
Turn over
AERA
SIHT
NI
ETIRW
TON
OD
AERA
SIHT
NI
ETIRW
TON
OD
AERA
SIHT
NI
ETIRW
TON
OD
PMT
(c) The total number of electrons in all the occupied p orbitals in a chloride ion, Cl–, is
(1)
A 5
B 6
C 12
D 18
(d) Which of these isoelectronic ions has the largest ionic radius?
(1)
A N 3–
B O 2–
C Na +
D A l3+
(Total for Question 1 = 4 marks)
Question
Mathematics
Edexcel2019
The standard molar enthalpy change of neutralisation is the enthalpy change when
an acid and an alkali react under standard conditions to form one mole of water.
(a) An experiment was carried out to determine the enthalpy change of
neutralisation for the reaction between propanoic acid and sodium hydroxide.
The equation for this reaction is
CH CH COOH(aq) + NaOH(aq) (cid:111) CH CH COO–Na+(aq) + H O(l)
Question
Mathematics
Edexcel2019
2 3 2 2
Question
Mathematics
Edexcel2019
2 4
Deduce two ionic equations to show how cobalt(II) ions catalyse the reaction in
acidic solution. State symbols are not required.
(2)
Question
Mathematics
Edexcel2019
Draw the dot-and-cross diagrams of these ions.
Use dots ( • ) for the hydrogen electrons and crosses (×) for the oxygen electrons.
(2)
Question
Mathematics
Edexcel2019
4 2 2
The K expression for this equilibrium is
c
(1)
[Fe]×[H O]
A K = 2
c [Fe O ]×[H ]