Given a scientific passage and an answer, generate a question for the given answer.

Passage: Refracting and reflecting telescopes are optical telescopes that use lenses to gather light. Answer: light
Refracting and reflecting telescopes are optical telescopes that use lenses to gather what?

Passage: Life Cycle of a Conifer Pine trees are conifers (cone bearing) and carry both male and female sporophylls on the same mature sporophyte. Therefore, they are monoecious plants. Like all gymnosperms, pines are heterosporous and generate two different types of spores: male microspores and female megaspores. In the male cones, or staminate cones, the microsporocytes give rise to pollen grains by meiosis. In the spring, large amounts of yellow pollen are released and carried by the wind. Some gametophytes will land on a female cone. Pollination is defined as the initiation of pollen tube growth. The pollen tube develops slowly, and the generative cell in the pollen grain divides into two haploid sperm cells by mitosis. At fertilization, one of the sperm cells will finally unite its haploid nucleus with the haploid nucleus of a haploid egg cell. Female cones, or ovulate cones, contain two ovules per scale. One megaspore mother cell, or megasporocyte, undergoes meiosis in each ovule. Three of the four cells break down; only a single surviving cell will develop into a female multicellular gametophyte, which encloses archegonia (an archegonium is a reproductive organ that contains a single large egg). Upon fertilization, the diploid egg will give rise to the embryo, which is enclosed in a seed coat of tissue from the parent plant. Fertilization and seed development is a long process in pine trees: it may take up to two years after pollination. The seed that is formed contains three generations of tissues: the seed coat that originates from the sporophyte tissue, the gametophyte that will provide nutrients, and the embryo itself. Answer: monoecious
Because conifers carry both male and female sporophylls on the same mature sporophyte, they are considered what type of plant?

Passage: Reactions and Compounds of Nitrogen Like carbon, nitrogen has four valence orbitals (one 2s and three 2p), so it can participate in at most four electron-pair bonds by using sp3 hybrid orbitals. Unlike carbon, however, nitrogen does not form long chains because of repulsive interactions between lone pairs of electrons on adjacent atoms. These interactions become important at the shorter internuclear distances encountered with the smaller, second-period elements of groups 15, 16, and 17. (For more information on internuclear distance, see Chapter 7 "The Periodic Table and Periodic Trends", Section 7.2 "Sizes of Atoms and Ions" and Chapter 8 "Ionic versus Covalent Bonding", Section 8.2 "Ionic Bonding". ) Stable compounds with NN bonds are limited to chains of no more than three N atoms, such as the azide ion (N 3). Nitrogen is the only pnicogen that normally forms multiple bonds with itself and other second-period elements, using overlap of adjacent np orbitals. Thus the stable form of elemental nitrogen is N 2, whose NN bond is so strong (DNN = 942 kJ/mol) compared with the NN and N=N bonds (DNN = 167 kJ/mol; DN=N = 418 kJ/mol) that all compounds containing NN and N=N bonds are thermodynamically unstable with respect to the formation of N2. In fact, the formation of the NN bond is so thermodynamically favored that virtually all compounds containing NN bonds are potentially explosive. Again in contrast to carbon, nitrogen undergoes only two important chemical reactions at room temperature: it reacts with metallic lithium to form lithium nitride, and it is reduced to ammonia by certain microorganisms. (For more information lithium, seeChapter 21 "Periodic Trends and the ". ) At higher temperatures, however, N2 reacts with more electropositive elements, such as those in group 13, to give binary nitrides, which range from covalent to ionic in character. Like the corresponding compounds of carbon, binary compounds of nitrogen with oxygen, hydrogen, or other nonmetals are usually covalent molecular substances. Few binary molecular compounds of nitrogen are formed by direct reaction of the elements. At elevated temperatures, N2 reacts with H2 to form ammonia, with O2 to form a mixture of NO and NO2, and with carbon to form cyanogen (NCCN); elemental nitrogen does not react with the halogens or the other chalcogens. Nonetheless, all the binary nitrogen halides (NX3) are known. Except for NF3, all are toxic,. Answer: four
What is the most electron-pair bonds a nitrogen atom can participate in?