The decline of the Songhai Empire in the 16th century was partly due to
Internal unrest and external attacks
Arab invasions
British colonial expansion
Portuguese trade restrictions
Correct answer is A
The decline of the Songhai Empire in the 16th century was due to a combination of internal unrest and external attacks, particularly from the Moroccan army. The other options are not historically accurate.
Which of the following physical properties decreases down a group in the periodic table?
Atomic radius
Ionic radius
Electropositivity
Electronegativity
Correct answer is D
No explanation has been provided for this answer.
The number of electrons in the valence shell of an element of atomic number 14 is?
1
2
3
4
Correct answer is D
No explanation has been provided for this answer.
An increase in temperature causes an increase in the pressure of a gas because?
it decreases the number of collision between the molecules
the molecules of the gas bombard the walls of the container more frequently
it increases the number of collision between the molecules
it causes the molecules to combine
Correct answer is B
The temperature of the gas is proportional to the average kinetic energy of its molecules. Faster moving particles will collide with the container walls more frequently and with greater force. This causes the force on the walls of the container to increase and so the pressure increases.
The shape of ammonia molecule is?
trigonal planar
octahedral
square planar
tetrahedral
Correct answer is A
No explanation has been provided for this answer.