The cell membrane acts as a semi-permeable barrier in plants. In other words, is in charge or control of what comes in and out of the cell.
Answer: A balloon is charged by a process of frictional charging and the object is getting charged by the process of induction.
Explanation:
When two bodies are rubbed against each other, charging by friction or rubbing occurs. The electropositive object loses electrons to electronegative object. Thus, when balloon is rubbed on a wall, it becomes charged.
The charged balloon is able to attract an uncharged object by inducing charge on it without the two objects touching each other. Electrostatic force acts between two charged objects. Charged balloon causes electrons to move at one end thereby inducing opposite charge in the object and thus, charged balloon is able to attract uncharged object.
Answer:
Rutherford was the first scientist who proposed the nuclear model of the atom. According to his atomic model, most of the space of an atom is empty, while the nucleus containing protons and neutrons lie at the center of the atom while electrons revolve around nucleus in definite orbits.
If we talk about studies of some other scientists like Dalton, Neil Bohr and JJ Thomson, they all are compatible with Rutherford's results to a large extent.
For example: Dalton's atomic model assumed that atoms of any substance are similar in size and atoms react to form compounds. Rutherford's concept indicated that atoms contain electrons and they are in a specific number which can be shared to form compounds.
If we talk about Bohr's model, it states that electrons revolve around nucleus in specific shells, this again is compatible with Rutherford's results which gave the concept of shells.
If we talk about Thomson's Plum pudding model, that describe atom as negative particles floating within a soup of diffuse positive charge. This is also compatible with the results of Rutherford that state that negative electrons surround positive nucleus.
Rutherford's model was best atomic model but still it took help from many previous studies and therefore was compatible with the results of old models.
Hope it help!
-two significant figures
-four significant figures
-One significant figure
-four significant figures
-two significant figures
-three significant figures
-three significant figures
Explanation:
1
Number of nucleon =
Molarmassofnucleon
Massofatom
=
1.6726×10
−24
g/nucleon
3.32×10
−23
g
=19.8=20(approximately)
It is given that element comprises of 2 atoms
Hence,number of nucleon = 2×20=40
2
You have 4.70 mol H2O
There are two H atoms in 1 molecule H2O.
Therefore, there must be 2*4.70 = 9.40 mols H in 4.70 mols H2O.
How many mols O in 4.70 mols H2O? That's 4.70 mols, of course.
Said another way, you have 2 mols H for every 1 mol H2O and 1 mol O for every 1 mol H2O.
So for 50 mols H2O you have 100 mols H and 50 mol O.
