Answer:
22)convex
23)sun (sunlight reflect of the off the surface of the moon
24)because of the way the atmosphere interacts with sunlight
25) transparent : glass,contact lenses,water,air
translucent: wax paper, oil paper, thin sheets
opaque : plastic, wood, leather
26)when light react with opaque: none of it passes though
when it reacts with transparent : it passes through
when it react with translucent : only some of it passes through, the light does not pass directly through the material
Explanation:
24 blue light is scattered in all directions by the tiny molecules of air in earth's atmosphere
The nitrite ion has one less oxygen than the nitrate ion. Nitrate is NO3-1 while the nitrite ion is NO2-.
You should take note that the question is about stability. A compound is stable if it does not easily react with other elements. Hence, its reactivity must be low. As you move down the group, reactivity decreases. So, the halide at the very bottom is the least reactive. It would then be logical that the most stable conjugate base is I⁻ and the least stable conjugate base is the most reactive which is F⁻.
Answer:
Explanation:
The usefulness of a buffer is its ability to resist changes in pH when small quantities of base or acid are added to it. This ability is the consequence of having both the conjugate base and the weak acid present in solution which will consume the added base or acid.
This capacity is lost if the ratio of the concentration of conjugate base to the concentration of weak acid differ by an order of magnitude. Since buffers having ratios differing by more will have their pH driven by either the weak acid or its conjugate base .
From the Henderson-Hasselbach equation we have that
pH = pKa + log [A⁻]/[HA]
thus
0.1 ≤ [A⁻]/[HA] ≤ 10
Therefore the log of this range is -1 to 1, and the pH will have a useful range of within +/- 1 the pKa of the buffer.
Now we are equipped to answer our question:
pH range = 3.9 +/- 1 = 2.9 through 4.9
