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sweet-ann [11.9K]
3 years ago
9

Brownian motion is

Chemistry
1 answer:
ioda3 years ago
6 0

Answer: A.

Explanation:

Brownian motion is the random motion of a particle as a result of collisions with surrounding gaseous molecules. Diffusiophoresis is the movement of a group of particles induced by a concentration gradient. This movement always flows from areas of high concentration to areas of low concentration.

Example:  The movement of pollen grains on still water. Motion of dust motes in a room (though largely influenced by air currents).

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The Geocentric and the Heliocentric models are descriptions of the universe known at the time when these models were developed.
RSB [31]

Answer:The Geocentric and the Heliocentric models are descriptions of the universe known at the time when these models were developed. The main difference between the two models is the perceived center of the known universe. According to the geocentric model, Earth is the center of the known universe

Explanation:I answerd the question before in Earth Science

8 0
2 years ago
Sperm can be carried by _____ grains. ANSWERSSSSSSSSSSSSSSSSS O spore O stamen O pollen
7nadin3 [17]

What is pollen in the reproduction cycle of flowering plants?

A pollen grain is a microspore containing the male gametophyte, usually reduced to two undivided cells, each with one haploid (n) nucleus. These cells are surrounded by a very resistant wall, the exine, which generally has apertures, zones with less resistance which will allow the germination of the pollen tube.

Explanation of the reproduction cycle (cf diagram above)

A given species produces flowers bearing stamens. According to species, these flowers can be unisexual (stamens only) or bisexual (stamens and carpels).

The stamen anthers include 4 pollen sacs containing sporogenous cells (diploid=2n). These sporogenous cells undergo meiosis, each producing 4 microspores (haploid=n). Two nuclei are then formed by mitosis : the vegetative nucleus and the generative nucleus. The latter divides to form 2 sperms. Simultaneously the wall of the microspores becomes thicker and takes the characteristic shape of the species : it is a pollen grain (see: What are the morphological characteristics of pollen and spore grains?). In the majority of species, the 4 grains (resulting from the 4 microspores) split up into single grains; in some cases, they remain together (tetrad = group of 4 grains). When mature, pollen grains are released by the opening of the anthers.

A pollen grain is aimed at reaching another flower of the same species, bearing carpels. The ovaries contain ovules, in which meiosis occurs, then mitoses. It results in an embryo sac with 8 nuclei, among which an egg cell and 2 central cells. When a pollen grain arrives on another flower (see : How are the spores and pollen grains transported?), it is received by the stigmas.

The pollen grain germinates through an opening of the wall: the vegetative nucleus develops into a pollen tube which is guided by the style to the ovary, then enters the micropyle of an ovule. The pollen tube releases 2 sperm nuclei into the ovule: one of the sperms fuses with the egg cell into a zygote (2n), while the other sperm fuses with central nuclei and gives rise to albumen (= food source). There are generally several ovules in an ovary : each one can be fertilized by a distinct pollen grain.

Each fertilized ovule and its albumen form a seed that will develop into a new individual of this species. hope it works

4 0
3 years ago
Read 2 more answers
PLEASE NO LINKS, GIVING BRAINLIEST, 18 POINTS , THANKS AND 5 STAR!!!!!!!!
Korvikt [17]

Answer:

2nd one In my opinion....

5 0
2 years ago
Determine the electron geometry (eg) and molecular geometry (mg) of CO2.
eimsori [14]

Answer:

eg=linear, mg=linear

Explanation:

First of all, it must be stated that most triatomic molecules are either linear or bent. This depends on the electron geometry of the molecule and the number of bonding groups, multiple bonds and lone pairs present.

CO2 contains four regions of electron density and two bonding groups. For a specie containing two bonding groups, a linear molecular geometry is expected with an angle of 180°.

For a specie having two bonding groups and no lone pairs with multiple bonds, the expected electron geometry is also linear.

6 0
3 years ago
An iron bar of mass 841 g cools from 84°C to 7°C. Calculate the heat released (in kilojoules) by the metal.
Oduvanchick [21]

Answer:

28.75211 kj

Explanation:

Given data:

Mass of iron bar = 841 g

Initial temperature = 84°C

Final temperature = 7°C

Heat released = ?

Solution:

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

specific heat capacity of iron is 0.444 j/g.°C

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = 7°C - 84°C

ΔT = -77°C

By putting values,

Q = 841 g × 0.444 j/g.°C × -77°C

Q = 28752.11 j

In Kj:

28752.11 j × 1 kJ / 1000 J

28.75211 kj

8 0
3 years ago
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