CHEMISTRY HIGH SCHOOL

Prehistory can be described as _____.what happened last year
what happened millions of years ago
the time prior to the use of written records

Answers

Answer 1
Answer: The way we usually think of history is the time of written records; or similar records(auditory, video) when we have direct evidence of what happened as opposed to reconstructing it from archaeological evidence. Pre-history is the time before this:  the time prior to the use of written records

Related Questions

Water molecules attract to one another to form what kind of bonds?
What is the mass of 1 mole of Na3,PO4?
Consider four elements from Group 7A: fluorine in the second period, chlorine in the third period, bromine in the fourth period, and iodine in the fifth period. Which element has the largest first ionization energy?
A pure solvent has a freezing point _________ the freezing point of a solution.a. equal to b. lower than c. higher than
Which part of an atom determines how it will react with other atoms? a. neutrons in the nucleus b. protons in the nucleus c. valence electrons d. innermost electrons

With the help of a reaction show that zinc is more reactive than iron.

Answers

3Zn+2Fe^(3+)\rightarrow 3Zn^(2+)+2Fe

List three organelles found in cells and describe their functions.

Answers

1. Nucleus: Contains genetic material, controls cell activities.

2. Mitochondria: Produces energy through cellular respiration.

3. Golgi apparatus: Modifies and packages proteins.

1. Nucleus: The nucleus controls the cell by storing DNA instructions. It affects cell growth, reproduction, and metabolism by regulating gene expression.

2. Mitochondria: Cellular respiration powers mitochondria. They convert foods into cell energy source ATP. Metabolism and cell signalling depend on mitochondria.

3. Golgi apparatus: It changes and packages endoplasmic reticulum proteins and lipids. Cisternae are stacked membranous sacs. The Golgi apparatus adds carbohydrates or lipids to proteins, organises them into vesicles, and guides them within or outside the cell. It is crucial for intracellular transport and secretion.

Learn more about organelles, here:

brainly.com/question/33512505

#SPJ3

nucleus: controls cell

cell membrane: controls what goes in and out of a cell

cytoplasm: where chemical reactions take place

At normal temperature and pressure, air has a density of 0.001184 g/mL. What is the mass of air in a room that is 3.07 m by 3.00 m by 3.77 m? Answer in units of kg.

Answers

1 ml = 1 cm3
The volume of the room is 34.7217 m3 or 34.721.700 cm3, so 34.721.700 * 0.001184 g/cm3= 41,1104928 kg.

37 Which general trends in first ionization energy and electronegativity values are demonstrated by Group 15 elements as they are considered in order from top to bottom?(1) The first ionization energy decreases and the electronegativity decreases.(2) The first ionization energy increases and the electronegativity increases.
(3) The first ionization energy decreases and the electronegativity increases.
(4) The first ionization energy increases and the electronegativity decreases.

Answers

Correct answer: The first ionization energy decreases and the electronegativity decreases.

Reason:
As we move from top to bottom in a periodic table, atomic radius increases. Also, effective nuclear charge decreases. Due to this, energy required to remove the electron form valance shell decreases. Hence, ionization energy decreases from top to bottom.

In addition to this, metallic character increases from top to bottom. Metals have low  electronegativity as compared to non-metals. Hence, electronegativilty value decreases from top to bottom. 

The correct statement regarding the first ionization energy and electronegativity values in group 15 is as follows:

\boxed{\left( 1 \right){\text{ The first ionization energy decreases and the electronegativity decreases}}}

Further Explanation:

The amount of energy needed for the removal of the most loosely bound electron from a neutral isolated gaseous atom is termed as ionization energy, represented by IE. It depends on the ease of electron removal from the neutral atoms. If the electrons are removed easily, ionization energy will be less and vice-versa.

Ionization energy is called the first ionization energy when the first electron is removed from the atom. It is shown by \left( {{\text{I}}{{\text{E}}_{\text{1}}}} \right). Similarly, if the second electron is removed, ionization energy becomes the second ionization energy \left( {{\text{I}}{{\text{E}}_{\text{2}}}} \right).

The tendency of any element for electron attraction towards itself in a chemical bond is known as electronegativity. More the attracting tendency of the atom for electron, higher will be its electronegativity and vice-versa.

Atomic number and number of shells increase while going down group 15. Due to this, atomic size increases in the group from top to bottom. This increase in size results in weaker attractions between the outermost electrons and the atomic nucleus. So electrons are removed easily and therefore the first ionization energy decreases down this group.

Since atomic size increases from top to bottom of group 15, the attraction between the atomic nucleus and the electrons decreases. Therefore electronegativity also decreases down this group.

Therefore both the first ionization energy and electronegativity decrease down group 15.

Learn more:

  1. Rank the elements according to first ionization energy: brainly.com/question/1550767
  2. Arrange the following elements from greatest to least tendency to accept an electron: brainly.com/question/2107660

Answer details:

Grade: Senior School

Chapter: Periodic classification of elements

Subject: Chemistry

Keywords: ionization energy, first ionization energy, electronegativity, attraction, group 15, decrease.

In the past, investigators would look at which two types of cues when trying to determine if someone was lying? Biased and unbiased


Verbal and non-verbal


Quiet and loud


Simple and complex

Answers

Answer : Verbal and non-verbal communication wad used by Investigators in the past when trying to determine if someone was lying.

Explanation: In the Verbal communication information is transferred from one person to other by speaking.

Non-verbal communication includes Facial expressions , eye contact , body language, eyes blinking etc.

If someone is lying he or she will easily dermined by applying above things.
Verbal and nonverbal.

They would look for shakiness of the voice (verbal) or darting eyes (nonverbal), and other things to that same effect.

Which diagram below shows the pathway of energy through an ecosystem? A.producer → carnivore → herbivore

B.producer → herbivore → carnivore

C.herbivore → producer → carnivore

D.carnivore → herbivore → producer

Answers

the answer is B. producer,herbivore, carnivore 
Other Questions
The ____ contains the highest concentration of ozone.a. troposphere c. stratosphere b. mesosphere d. exosphere
When two intermediate chemical equations are combined, the same substance that appears in the same phase can be canceled out, provided thatA) it is a reactant in one intermediate reaction and a catalyst in the other reaction. B) it is a product in one intermediate reaction and a catalyst in the other reaction. C) it is a reactant in one intermediate reaction and a product in the other reaction. D) it is a reactant in both of the intermediate reactions.
Please help ASAP ty :)
How many molecules are in 2.6 grams H4C