Which of the following substances contains a covalent bond?
a. NaCl
b. SO2
C. CaO
d. MgCl2

Answer:

chloroplast

Explanation:

i took the test

Answer:

¹⁶⁸₇₉Au

Explanation:

The symbol of the atom is given as;

          ¹⁷²₈₁Tl

If undergoes a nuclear reaction and it ejects an alpha particle;

 An alpha particle is the same as an helium atom

      ¹⁷²₈₁Tl  →  ₂⁴H   +     ₐᵇK

K is the hypothetical symbol of the new atom

b is the new mass number

a is the new atomic number;

 Conserving mass number;

        172  = 4 + b

        b  = 172  - 4  = 168

Conserving atomic number;

        81  = 2 + a

        81 - 2  = a

         a  = 79

The new compound is gold with a symbol of;

       ¹⁶⁸₇₉Au

Answer:

Under the earth's surface, rocks melt, metamorphize, and crystalize.

Explanation:

Metamorphic and Igneous rocks are basically dependant on the heat/pressure of the environment under the surface :) Melting, metamorphosing and crystallization all occur under earth's surface.

The specific processes in the rock cycle that occur beneath the Earth surface are :

Under the Earth surface the specific rock cycle processes that leads to the formation of the different types of rocks includes;  Melting, metamorphization and rock crystallization.

Metamorphic rocks are formed from other rocks ( sedimentary and igneous rocks)  due to the change in temperature and this process is metamorphization. while igneous rocks are formed from molten rocks caused by the melting process. Sedimentary rocks are formed by the deposition of sediments from weathering of existing rocks this is the  crystallization process.

Hence the specific process in the rock cycle that occur beneath the Earth's surface are : Melting, metamorphosing and crystallization.

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Answer:

valence electrons

Explanation:

This is because the valence electrons determine if an atom of an element can bond with other elements.

Answer:

false

Explanation:

Note that the solvent is the substance that is present in the greatest amount. Many different kinds of solutions exist. For example, a solute can be a gas, a liquid or a solid. ... Note that in each case, the solute particles are uniformly distributed among the solvent particles.

Answer:

C

Explanation:

I think that this answer Is more personal but they should try to limite animal cruelty in their research.

Answer:

C

Explanation:

Answer:

Calcium has a charge of positive 2 not negative

Explanation:

Answer: this ones old do you still need help on this one?

Explanation:

Answer:

Astronaut

Explanation:

Astronaut.He is 100kgs

Answer:

b) 1.0g

Explanation:

C=m

MV

where Cis concentration

m is mass of substance

M is molar mass

V is volume of substance

To find m

CMV=m

but M = 23+16+1

= 40

0.1×40×0.25=m

1.0=m

Answer:

Gas

Explanation:

Legend primordial element element by radioactive decay Atomic number color: red=gas

Answer: 57 neutrons

Explanation: Ruthenium has an atomic number of 44, meaning it has 44 electrons, 44 protons, and 57 neutrons.

Answer:

57 neutrons

Explanation:

Ruthenium has atomic number of 44, that is, it contains 44 electrons distributed in atomic orbitals and its nucleus has 44 protons and 57 neutrons (Figure 1). Electron distribution in atomic or molecular orbitals is called electron configuration which for Ru and the other group 8 chemical elements is shown in Table 1.

Answer:

Malachite

Explanation:

Malachite is the only listed compound that must contain copper and oxygen.

Copper and oxygen are both elements found on the periodic table. They have the following symbols;

         Copper  = Cu

         Oxygen  = O

From the given choices, only option 1 has the symbol Cu and O.

So only malachite contains both copper and oxygen.

Answer:

Explanation:Metalloids may act either like metals or nonmetals in chemical reactions. Most metalloids have some physical properties of metals and some physical properties of nonmetals. They fall between metals and nonmetals in their ability to conduct heat and electricity. They are shiny like metals but brittle like nonmetals.

Answer: She could have put a steel spoon into the vessel. The correct option is A.

Explanation:

When a candle wax is passed through heat, it is capable of melting within 10- 15 minutes of boiling. Therefore it is not capable of looking the same after 30 mins of heating.

When sugar is put into water it dissolves. When heated it has the ability to crystallize out after water is evaporated but doesn't retain its shape.

A piece of chocolate will melt the instance it comes in contact with any form of heat.

A steel spoon is an alloy metal which is not capable of melting by boiling in water for just 30 minutes. A steel is an alloy of Iron and carbon which melts when superheated at the temperature of 1510 degrees.

Answer: 4 atoms.

Explanation:

Answer:

Pore spaces filled with water

Answer:

132g

Explanation:

The reaction equation is given as:

          CaCO₃  →  CaO  + CO₂

Given;

 Number of moles of CaCO₃  = 3 moles

Unknown:

Mass of CO₂ produced  = ?

Solution:

From the balanced reaction equation;

          1 mole of CaCO₃ will produce 1 mole of CO₂;

         3 mole of CaCO₃ will then produce 3 moles of CO₂

To find the mass of CO₂;

  Mass of CO₂ = number of moles x molar mass

      Molar mass of CO₂  = 12 + 2(16) = 44g/mol

 Mass of CO₂ = 3 x 44  = 132g

Answer:

The continuous motion of air and water distributes the sun's energy.

Explanation:

The continuous motion air and water helps to distribute the sun's energy throughout the earth, and thus maintain fairly constant average temperatures.

The equatorial regions of the earth receives more heat than regions of higher latitudes. By means of convection air currents, whereby hotter and lighter air from the equatorial regions is circulated for colder and denser air from the regions of higher latitudes, heat is distributed between these regions.

Also, the heat of surface waters at the equatorial regions is circulated in convection currents as seas and oceans move around, to other regions of the earth in order to maintain a fairly constant average temperature.

Answer:

the continuous motion of air and water distributes the suns energy.

Explanation:

160 grams of I-131 were in the original sample if the half-life is 8 days.

In a chemical reaction, the time taken for the concentration of that substance to become half of its initial value is called half-life. This term is used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay .

The amount left N after n half lives of a radioactive element with original amount N₀ is given as:

N= N₀ (1/2)ⁿ

Given, half life of Iodine-131 is 8 days

n= 40/8= 5

5= N₀ (1/2)⁵

N= 32 * 5

= 160 grams

Hence, the original amount amount of  I-131 will be 160 grams.

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Answer:

sunlight

Explanation: i go to school

Answer:

light/sunlight

Explanation:

Chlorophyll's job in a plant is to absorb light—usually sunlight. The energy absorbed from light is transferred to two kinds of energy-storing molecules. Through photosynthesis, the plant uses the stored energy to convert carbon dioxide (absorbed from the air) and water into glucose, a type of sugar.

Hope this helped!

Explanation:

I think pebbles because the pebbles can be different sizes and have bigger gaps in between them so the water will go through quicker.

hope this helps srry if wrong