the temperature of 550g of water is changed from 20.8°C to 25.3°C. How much heat did this sample absorb?

10,370.25J

Explanation:

Given the following :

Mass of water = 550g

T1 = 20.8°C

T2 = 25.3°C

Temperature change = (T2 - T1) = (25.3 - 20.8)°C = 4.5°C

Specific heat capacity of water = 4.19Jg^-1C^-1

Recall:

Q = mc∆T

Where ∆T = temperature change, Q = quantity of heat c = specific heat capacity of water, m = mass of water in gram

Q = 550 × 4.19 × 4.5

Q = 10,370.25J

33: i think it’s b

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.