Answer:
Close to the calculated endpoint of a titration - <u>Partially open</u>
At the beginning of a titration - <u>Completely open</u>
Filling the buret with titrant - <u>Completely closed</u>
Conditioning the buret with the titrant - <u>Completely closed</u>
Explanation:
'Titration' is depicted as the process under which the concentration of some substances in a solution is determined by adding measured amounts of some other substance until a rection is displayed to be complete.
As per the question, the stopcock would remain completely open when the process of titration starts. After the buret is successfully placed, the titrant is carefully put through the buret in the stopcock which is entirely closed. Thereafter, when the titrant and the buret are conditioned, the stopcock must remain closed for correct results. Then, when the process is near the estimated end-point and the solution begins to turn its color, the stopcock would be slightly open before the reading of the endpoint for adding the drops of titrant for final observation.
Answer:
- 1. Dimensions: The sheet can be cut into several smaller pieces.
- 2. Shape: the sheet can be formed into a paper ball or any other shape (using origami for example).
- 3. Color: You can use crayons to paint the sheet and change its color.
Explanation:
<em>Physical changes</em> do not change the chemical properties. They do not transform the compounds that form the substances. They do not break and or form chemical bonds.
When you change the form, the state (solid, liquid or gas), the color, you are just changing physical properties.
Only chemical changes change the compounds that form the substance. For instance, if you burn the <em>sheet of paper</em>, then you are causing a chemical change because the organic matter in the paper will react with oxygen forming CO₂ and water, but by cutting, folding, smashing, or coloring with crayons, the compounds in the<em> sheet of paper</em> do not change.
Answer:
4 g OF IODINE-131 WILL REMAIN AFTER 32 DAYS.
Explanation:
Half life (t1/2) = 8 days
Original mass (No) = 64 g
Elapsed time (t) = 32 days
Mass remaining (Nt) = ?
Using the half life equation we can obtain the mass remaining (Nt)
Nt = No (1/2) ^t/t1/2
Substituting the values, we have;
Nt = 64 * ( 1/2 ) ^32/8
Nt = 64 * (1/2) ^4
Nt = 64 * 0.0625
Nt = 4 g
So therefore, 4 g of the iodine-131 sample will remain after 32 days with its half life of 8 days.
Oxygen and water
Plants release water through osmosis and oxygen through stomata
