I need help pls! sooner is preferable than later! thank you!

Reagent: aqueous bromine

Observation with ethene: solution turns from brown to colourless.

Observation with ethane: solution remains brown

Explanation:

Unsaturated compound contain C - C double bond while Saturated compound contain C - C single bond. Alkenes with C - C double bonds (unsaturated) can undergo bromination reaction while alkanes (saturated) are not able to do so due to the absence of C - C double bonds.

the velocity you are looking for is made up of two parts: horizontally velocity, vh, and its vertical velocity, vv. the actual velocity of the ball will be these two parts added together, and because velocity is a vector then they will need to be added vectorially.  

neglecting air resistance etc etc.,  

the horizontal velocity component will be constant (because there is no accelerating force in the horizontal direction.  

vh = 8 ms-1  

the vertical velocity component has an accelerating force: 'g'.  

using v = u +at where a = g = 9.81 ms-2.  

the vertical component of velocity, vv = 0 + gt = vv =9.81 x 2  

vv = 19.62 ms-1 . the zero appears because the virtical component of velocity at time t=0 is zero. remember, the ball was thrown horizontally.  

how fast it will be moving (it actual path (being a parabola )) will be the vector sum of these two.  

adding vectorally gives: -  

v = sqr root (8^2 + 19.62^2) = sqr root(64+384.9) = 21.18 or 21.2 ms-1

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide