<h2>Answer:</h2>
Option B is correct.
b. extending outward is more economical than extending upward
<h2>Explanation:</h2>
people tend to move from rural areas to urban for the greater facilities that they can enjoy at cities. This urban sprawl is also very economic because people will get more chances of jobs, business and work hence improving the economy.
When organisms and plants died and sank to the bottom of swamps and oceans, brown soil-like materials called peat are formed. Over millions of years, the peat became covered with sand, clay and other minerals and the peat is converted into layers of sedimentary rocks. After a long time, different type of fossil fuels are formed.
Answer:
The cell membrane's main trait is its selective permeability, which means that it allows some substances to cross it easily, but not others. Small molecules that are nonpolar (have no charge) can cross the membrane easily through diffusion, but ions (charged molecules) and larger molecules typically cannot. A concentration gradient is a just a region of space over which the concentration of a substance changes, and substances will naturally move down their gradients, from an area of higher to an area of lower concentration.
In cells, some molecules can move down their concentration gradients by crossing the lipid portion of the membrane directly, while others must pass through membrane proteins in a process called facilitated diffusion.
Explanation:
there are your two reasons molecules cannot pass easily through the cell membrane and what part of the cell membrane helps them get through is concentration gradient
If the temperature is TC = 20 °C (T = 293 K), the speed of sound is v = 343 m/s. The equation for the speed of sound in air v = √γRTM can be simplified to give the equation for the speed of sound in air as a function of absolute temperature: v=√γRTM=√γRTM(273K273K)=√(273K)γRM√T273K≈331m/s√T273K. v=fλ.
Hope this helps
