145 hours.
Explanation: Riding a bicycle for one hour expends 505 kcal of energy. Given that one gram of body fat equals 7.70 kcal, and 1 pound of body fat is equivalent to 454 grams:
1 lb = 454 g; thus, 21 lb = 21 × 454/1 = 9534 g. Moreover, converting 9534 g of body fat gives us 9534 × 7.70 kcal/1 = 73411.8 kcal. If riding for one hour burns 505 kcal, then to lose 73411.8 kcal, it would require 73411.8 kcal x 1 hour/505 kcal = 145 hours.
<span>Quarks exist inside protons and neutrons but are not components of electrons.
Quarks are subatomic particles that possess mass and fractional (non-integer) electric charge.
Protons and neutrons are composed of quarks, whereas electrons are not, since electrons are considered energy carriers with charge rather than massive matter. Because quarks have mass, they cannot be part of electrons.</span>
Because they often have long half-lives, their radioactive persistence in the environment is lengthy.
Number 4
If you spot any errors in my English, please tell me, since I am not a native speaker.
Hi there! Calvin informed Marie that they could still incorporate solute until reaching 40 grams because the solution remained unsaturated. Unsaturated solutions denote situations where the solvent (water in this instance) can further dissolve more solute (here, KNO₃) considering the current pressure and temperature. This can be visually confirmed when additional solute does not lead to visible solid residues settling at the bottom of the flask, indicating that the dissolving rate surpasses the crystallization rate. Wishing you a pleasant day!
