In ammonia, a central nitrogen atom is bonded to three hydrogen atoms. similarly, boron trifluoride has a central boron atom bonded to three fluorine atoms. however, ammonia is pyramidal and boron trifluoride is trigonal planar in shape. which statement justifies this difference in their structure?
a. the lone pair of electrons in boron trifluoride increases the bond angle between the bonding pairs, giving it a planar structure.
b. the lone pair of electrons in boron trifluoride decreases the bond angle between the bonding pairs, giving it a planar structure.
c. the lone pair of electrons in boron trifluoride stabilizes the bond angle between the bonding pairs, giving it a planar structure.
d. the lone pair of electrons in ammonia increases the bond angle between the bonding pairs, giving it a pyramidal structure.
e. the lone pair of electrons on the nitrogen in ammonia decreases the bond angle between the bonding pairs, giving it a pyramidal structure.

Aforce of 34n stretches a very light ideal spring 0.73 m from equilibrium, what is the force constant (spring constant) of the spring? (a) 47n/m (b) 38n/m (c) 53n/m (d) 25n/m

1134567 a jet with mass m = 1.1 ă— 105 kg jet accelerates down the runway for takeoff at 2 m/s2. 1) what is the net horizontal force on the airplane as it accelerates for takeoff? 2.2*10^5 n your submissions: 2.2*10^5 computed value: 220000submitted: saturday, january 26 at 2: 41 pm feedback: correct! 2) what is the net vertical force on the airplane as it accelerates for takeoff? 0 n your submissions: 0 computed value: 0submitted: saturday, january 26 at 2: 41 pm feedback: correct! 3) once off the ground, the plane climbs upward for 20 seconds. during this time, the vertical speed increases from zero to 21 m/s, while the horizontal speed increases from 80 m/s to 95 m/s. what is the net horizontal force on the airplane as it climbs upward? n 4) what is the net vertical force on the airplane as it climbs upward? n 5) after reaching cruising altitude, the plane levels off, keeping the horizontal speed constant, but smoothly reducing the vertical speed to zero, in 13 seconds. what is the net horizontal force on the airplane as it levels off? n 6) what is the net vertical force on the airplane as it levels off?

Arod of some material 0.20 m long elongates 0.20 mm on heating from 21 to 120°c. determine the value of the linear coefficient of thermal expansion [in (degrees c)^-1] for this material.