Answer: C
Explanation:
In endothermic reactions, enthalpy is positive, and in exothermic reactions, enthalpy is negative, So, if enthalpy is positive, then it is an endothermic reaction, and hence is required for the reaction to occur.
Answer:
PBr5 is the formula of phosphorus pentabromide.
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Malleability described the property of physical deformation under some compressive stress; a malleable material could, for example, be hammered into thin sheets. Malleability is generally a property of metallic elements: The atoms of elemental metals in the solid state are held together by a sea of indistinguishable, delocalized electrons. This also partially accounts for the generally high electrical and thermal conductivity of metals.
In any case, only one of the elements listed here is a metal, and that’s copper. Moreover, the other elements (hydrogen, neon, and nitrogen) are gases under standard conditions, and so their malleability wouldn’t even be a sensible consideration.
Answer:
No
Explanation:
loss of electron doesn't affect the element.
only change in proton number can, as we notice in nuclear chemistry.
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Answer:
- Compress
- Fixed
- Melts
- Melting Point
- Freezing Point
- High
- Crystalline
- Lattice
- Unit cell
- Amorphous solids
Explanation:
Solids tend to be dense and difficult to <u>compress.</u>
They do not flow or take the shape of their containers, like liquids do, because the particles in solids vibrate around <u>fixed</u> points.
When a solid is heated until its particles vibrate so rapidly that they are no longer held in fixed positions, the solid <u>melts</u>.
<u>Melting point</u> is the temperature at which a solid changes to a liquid. The melting and <u>freezing point</u> of a substance are at the same temperature.
In general, ionic solids tend to have relatively <u>high</u> melting points, while molecular solids tend to have relatively low melting points.
Most solids are <u>crystalline</u>
The particles are arranged in a pattern known as a crystal <u>lattice</u>
The smallest subunit of a crystal lattice is the <u>unit cell</u>
Some solids lack an ordered internal structure and are called <u>amorphous solids.</u>