Answer:
i) 21 cm
ii) At infinity behind the lens.
iii) A virtual, upright, enlarged image behind the object
Explanation:
First identify,
object distance (u) = 42 cm (distance between object and lens, 50 cm - 8 cm)
image distance (v) = 42 cm (distance between image and lens, 92 cm - 50 cm)
The lens formula,

Then applying the new Cartesian sign convention to it,

Where f is (-), u is (+) and v is (-) in all 3 cases. (If not values with signs have to considered, this method that need will not arise)
Substituting values you get,
i) 
f = 21 cm
ii) u =21 cm, f = 21 cm v = ?
Substituting in same equation
v ⇒ ∞ and image will form behind the lens
iii) Now the object will be within the focal length of the lens. So like in the attachment, a virtual, upright, enlarged image behind the object.
Answer:
I need this for may schooling
Answer:
Different elements all have different amounts of electrons in there outter shell.
Explanation
If you look at a periodic table, the elements are all listed in "Groups" up at the top you'll see the numbers, or columns. Each column's number represent how many electrons there are in each particular element.
hope this makes sense....
<span> <span> <span> <span> CLIMATE: The amount of water in the air and the temperature of an area are both part of an area’s climate. Moisture speeds up chemical weathering. Weathering occurs fastest in hot, wet climates. It occurs very slowly in hot and dry climates. Without temperature changes, ice wedging cannot occur. In very cold, dry areas, there is little weathering. </span> <span> SURFACE AREA<span>-
Most weathering occurs on exposed surfaces of rocks and minerals. The more surface area a rock has, the more quickly it will weather. When a block is cut into smaller pieces, it has more surface area. So, therefore, the smaller pieces of a rock will weather faster than a large block of rock</span> </span> <span> ROCK COMPOSITION<span>-
Some minerals resist weathering. Quartz is a mineral that weathers slowly. Rocks made up of minerals such as feldspar, calcite, and iron, weather more quickly.</span> </span> <span> Pollution speeds up weathering. Factories and cars release carbon dioxide and other gases into the air. These gases dissolve in the rainwater, causing acid rain <span>to form. Acid rain contains nitric and sulfuric acid, causing rocks and minerals to dissolve faster. </span> </span> </span> </span> </span>